My friend (C) was sold out for selling marijuana by a prior friend of his, (K) and was given a felony charge along with all the other ramifications that come with that.

I moved in with C about a year ago, and it was clear he did not like my closest friend (S) due to S having been romantically involved with C in the past and C now having a long term girlfriend who lives with us. He tolerated S's presences, but was uncomfortable with her being around. His girlfriend has never has a problem with S. 

This week, C was informed that S was friends with and communicating with K on Facebook. He told me I was not to have S around because of this, as C is still doing the same business he has in the past.

I have stated that I know S, trust her implicitly, and know she would not tell K anything involving other people, especially not anything like this. C has retained his position, and I dropped it. 

The lease for the rental is not in either of our names officially, but the landlord has told me I am the one who she considers it under. I pay exactly as much as C does for rent, utilities, and other bills here, and I don't believe banning S is fair or effective.

I want to have S over.. The way I see it, if S wanted to make something like this a problem, she already could have. We aren't moving, so she still has all the information on C's business and location, regardless of this ban. If anything, S would have more incentive to get C in trouble, although she has not and would not consider that an option because she's genuinely a good person. I've been her friend for about 9 years. 

WIBTA by confronting C and demanding to be allowed to have S over?