I'll answer your questions one by one, marked by a *:
1* Somebody got buttmad about Vince's post and walked out.
2* Since they aren't coming back and there isn't anything we can do but make a mountain out of a molehill by hanging Vince just to get one person to come back, no.
3*Newer players are registering and posting, but it is mostly the old guard (rofl, am I old guard now?) who post regularly.
4* It has nothing to do with RP in EVE. This is a Backstage issue.
5* Short answer, no.
Long answer... Vince's meme does break forum rules by most measurements, but it's tolerated because we all known him well enough to realize it's a joke. We all go "Haw haw!" and move on with our lives.
Newer players don't know him, may not understand that, and yeah, some of them walk away, apparently. If you check the threads of actual new people, a lot of them do seem surprised and/or question Vince's post, wondering if they had done something wrong. Until now, I don't think anyone quit.