It's not my personal tastes as a player - any M/M scenes he gets into would fade to black by preference - but I thought about it for a bit and realized it just made sense. He's on a mission to personally spread his progeny across as many universes as he can in the service of Shub-Niggurath, and if the Great Old One can affect his seed to ensure the resultant children are corrupted by Her power, there's no reason said child can't use a man as a host as well. Any such Mr. Seahorse 'birth' would inevitably be fatal, chestburster-style, but that's not his problem. Omnisexual would be a more accurate descriptor than simple bisexual, but neither is 100% correct since his primary criteria is being sufficiently humanoid enough to couple with and incubate the resultant 'child'.