I mean, it's also not how the warp scale works based on principles shown in previous episodes of Star Trek. It's just all around ridiculous.

It's just bad writing. They could literally all come back to earth, get the same injection Tom and Janeway had and in a couple of days they would be back to Earth. That is without considering that warp 10 was a side project of a lone helmmen stranted on the other side of the galaxy, just think what the best federation scientists would do with the appropriate reaources, in a couple of years they would eliminate any adverse effect.

You can't just drop one of the most relevant scientific breakthrough of the century as a story for a single episode and then completely forget about it.