The justification will be a consequentialist argument, we sacrificed/tortured animals and in exchange we gave this to humanity; the overall calculus is a net positive.

This post shows the very worst of the equation, and they will bring up the best, maybe some people that couldn't walk that now can, or some psychological disease for which this contributed to the cure.

They will probably bring up numbers like, this damaged hundreds, but will benefit hundreds of thousands.

This is not the first time society accepts such a compromise. There are innocent people in jail serving life sentences, because every criteria will have false positives. We can undo this wrong right now, we just have to let everyone out of prison.