I would move immediately beyond the point of whether TM is religion, and take it as such. There are religious schools in the US and many other places, that promote performing rituals related to a specific religion as part of their curriculum. Some of them even promote a reasonable theological perspective, but that seems to be optional (yes, I am being sarcastic about catholic schools...)
Hence, I would have no problem with TM creating private schools that promote whatever approach they have to life, and have scholar success with them.
I am not however an advocate of religious-biased schools. I would like schooling to be totally separated from religion, and religious education to be taken outside regular school hours, if at all (I am against teaching religion to children, unless it is a general overview of religions as a whole taught in a cultural, societal and historical context. I feel strongly that you cannot teach faith, you can teach values such as humanistic values, but that does not need to be connected to any religion in particular). I would have no problem with TM schools more than catholic ones. I don't have a problem with TM making a business of it either, provided it is treated as a business, and that there are appropriate checks on the rigour of the system. In the US context, I would just be afraid of the "cult/sect" issue.
I moved to Ireland (the Republic, that's the free part of the island) about 3 years ago and my kids are in Irish schools, though I have not understood yet if they are private or public. There is a rather outdated promiscuity between the catholic church and the Irish state (by European standards), if not formally, at least in effect. They are very good schools, though unfortunately, like most in Ireland, still clinging to the gender-separate approach (schools for boys, schools for girls), but that's not the point. There was a recent minor change in the education system in high schools, and one of my kids who just started the secondary education now has to do a course in religion.
I asked him to be excused, but I was told that while this might be possible, it would not be accepted unless for strong reasons. Apparently, the concept is that this is not a course on catholic faith (a course on faith... like that's possible!) but a school subject that covers all religions. I was not sure it would do so unbiasedly, but still, it won't kill him, so he's on it. However, he seems to find no difference between it and religious education Sunday-school type. I talked to his teacher a while ago and she found it quite funny to have him around. Apparently, in the exams/tests he tries to answer questions in a rational manner, finding rational justifications for what he his asked (he's 14). She said she never looked at many things from that perspective and she finds this funny. I find it appaling, as it means that most of the things that he is being taught in a SCHOOL subject are apparently irrational, that is, if you follow rational thought you get the wrong answer. Obviously, this is not good. My son will not learn faith (which could never be learned), what he is learning is that catholic religion doesn't make sense, that is, he is learning the wrong things. I am christian and theologically close to catholicism, I would like my children to eventually develop a Christian faith, but that is their choice and their calling, and this education isn't helping. The same happened to me, my religious education only made me run from it. I am Christian IN SPITE OF religious education.
The problem I have is that I don't think people have considered religious education from the perspective of learning, but consider it from the perspective of teaching. Teaching means someone bla-bla-bla on a given subject. What people that hear the teachings learn is not necessarily what the teacher intended. Learning takes the message and decodes, interprets and assimilates it according to the interests, beliefs and set of values of the individual.
The Christian, and particularly Catholic, approach to teaching is to force people into a given pattern of obedience, which is more designed to perpetuate the power of the Church than to make sure that individuals actually apply Christian principles in their daily life and relationships to others. The way to do this is old style scaring tactics: obey the Church or burn in Hell. As our society becomes increasingly free, youngsters are increasingly cynical about this and religion is being ritualised, not perceived. I estimate that around 90% of the Irish, Portuguese, Spanish and Italians (supposedly strong European catholics) wear catholicism on top of their skins like a shirt.
Because there is a cultural contextual link between catholicism and Irish society, or between Christianity and the "west" (Europe/America) it does not bother me too much that my children go through religious teaching. They are just experiencing what I did.
At the end of the day I think that the religious education does not matter much IF the country and society are free. Freedom of speech, of thought and of choice, will eventually allow individuals to brew their own choices regardless of their religious education (if religious education is used as part of a repressive, obedience, tactics of societal control, then it is worrying).
Because I am religious, I would prefer that religion is NOT taught at school, as it ends being counterproductive. I also think that catholicism is at its best when it is NOT mainstream and NOT associated to power. Power corrupts theology. To associate religious teaching to a public system, assuming that the country is, say, catholic, leads to this corruption, so it is a bad thing. The church is at its best when it is opposition to political systems and the inequalities they generate, and when it is associated to the socio-political system it ends up fighting for its own share of privileges and inequalities, in opposition to what it should be doing.
Unfortunately, it seems that few people share my views, at least in Ireland.