Here is the assumption, they assume it is still forming or just formed, nothing is evidenced.
They also assume the "hot jupiter" is 2 million years old, only based on the assumed age of the star, again not evidenced.
"Astronomers" like to put the cart before the horse...
In stellar metamorphosis, hotness is relative, if a gas giant is close to its parents star the hotness comes from the star.
There is also a caveat in all cases and that is interpretation of the light data, which may be completely wrong or not correct enough to make claims.