Well, if it was a private Church camp, I guess they do have the right to decide who gets to be there and who doesn't. Not that that makes it right.

Why did they send her home? Well, it sounds to me like that particular denomination was not a fan of homosexuals, or at least of homosexual behavior (it's not entirely clear to me which one it was). They see either the orientation or the sexual actions as a sin. Thus, your friend was violating the teachings of that denomination. She was given two options: apologize and never do it again or leave. Obviously she decided to leave.

Now, setting aside the issue of whether being gay is sinful or not, their actions make sense. They had come up with certain rules for their community to follow. Your friend violated those rules and then continued to refuse to follow them. It makes sense that she was kicked out of the community at that point.

Going briefly back to the subject of the sinfulness of being gay, I'm just going to leave this one alone. There are so many differing views inside the Christian community, and there are probably even some that I've never even heard of. That's what happens when you split off into a million different denominations that each have their own say on what's what and are all allowed to interpret the bible however they want to.

I'm Catholic and, while our Church does not condone homosexuality, they do make a point of saying that we need to accept them and love them. The actions of the church camp leaders you've brought up seem very unloving to me. To say that a person cannot even abide in the presence of believers if they are sinful is, well, incredibly hypocritical. We are all sinners and we all have our crosses to bear. The only way any of us can even hope to lead a holy life is with the help of both Christ and the Church, the community of believers.
My Church is all about community and seeking help from our Church family (those on Earth, those in Purgatory, and those in Heaven), so this whole community thing has been instilled in me since I was a child. To exclude someone from your community who is doing no harm seems very uncaring to me.

But then, that's just my views on the subject.