Trust problems are on your recruits' end, has nothing to do with their involvement in a group of friends with the sole difference being a tag that they wear to express their sense of belonging and pride.
The whole thing sounds silly, what I can understand is that you're against VU members having close friends/a group of friends that they chat with on discord just like any other group that hangs out and wanders in the streets.
if there happens to be an information leak, it is your members that aren't worthy of the membership, because if someone turns out to be exposing you out, then it's their problem and he should be sanctioned accordingly.
Either way, It is still possible to have private info leaked but you can't deprive people of having close friends and in this case, friends who define themselves as an organized group, because you're being paranoid, you can't be 100% sure your members are going to leak info but banning VU members from joining PL is outright exaggerated and a lazy attempt to put an end to this problem,
There is really no difference as few members from both sides may still be friends, but they don't belong to that gang, so if a VU member is idiot enough not to know how critical private information is and happens to have shared it with a member from the other side then you'll find out this decision is useless.