My point is not, If I like him or not, but that it doesn't make sense to even allow him into the group, the way, he threatens you with a knife. And If you let him into the group, he is quite frankly downright creepy in his delight of the misery and torture of others.
From a role playing standpoint, I think it makes sense. You're trying to pool all your resources together. Everyone with a tadpole working together to solve a problem. Yeah some of them are loose canons and liable to turn on you at any point, but for now, there's a sense of desperation holding everyone together. I could understand not trusting him enough to have him in your party though. For my character, as soon as he/she realizes Astarion has a tadpole, it's worth keeping him close. My character is probably more of a mediator though, trying to make everyone get along
