My first poly relationship was MFM. Now, while the two guys were, in many ways, dating, they were not in a sexual relationship with each other. However, they were often in sexual situations with me simultaneously (Does that qualify as a male unicorn? I certainly found it "magical") and were comfortable being that close. We had a all-sitting-around-th-house-naked kind of relationship.
My current partner is bi and I admit, I get really turned on by the idea of him with another guy. My husband has no desire to be that guy, but there are plenty of other options.
So ... I can't speak for the community as a whole, but my poly experience has been pretty guy/guy friendly.