You're a fool if you think that. If a vampire wants to do something, having someone know they're a vampire isn't going to be enough to stop them. They'll do it despite that and possible even in spite of it.
As Suzaku has already explained that the list is voluntary, then all those who worry about those things have the right to sign it. Those who don't won't have to. Easy, no? That doesn't change the fact that anyone who is on it should be able to know the names of everyone who gets to see the list. It's not really all that safe and fair if vampires are trusting enough to reveal themselves, but we don't get to know who are the ones we're trusting ourselves to.