Technically she's correct, if not particularly wise. The problem is it sets you up to be reactive instead of proactive; you're waiting for something to happen first before housing them separately, which may be a lost toe, damaged beak, or worse. I'm shocked a vet wouldn't be more proactive about a situation like this, they are usually more cautious.
Then again, we see time and again vets generally are poor resources for ekkie non-medical care, period. Most of the time they don't even get the diet right.
There are no social benefits to keeping them together at this point, that's simply made up.
Look, don't be foolish - last time Ill say this before letting it go and letting you make your own mistakes - your vet gave you bum advice on this. Listen to those with plenty of experience here who want nothing but the best. You're playing with fire and setting yourself up to get burned, badly.
Be wise, and be proactive. Your girls are counting on you.