Do you share Velikovsky's understanding that Venus was a comet until rather recently?
Planets with brilliant comet-like tails such as Velikovsky described have been documented in exo-solar systems, so the characterization is a potentially reasonable one. Likewise, Venus has a remnant ion tail that behaves in the same way as a comet's tail, pointing away from the sun and getting stronger as Venus approaches the sun. At Venus's closest approach to the Earth, the tail stretches millions of miles out into space as far as the Earth. That fact, along with the apparent rotational resonance that Venus exhibits with the Earth (Venus always points the same face to the Earth at that inferior conjunction), the idea that Venus might have made a close approach to the Earth at some point in the recent past seems credible.
Based on what is currently known about exo-planet formation and about the planet Venus itself, I see nothing to preclude Venus having been created by an impact on Jupiter in much the way that Velikovsky describes.