It helps that Ranli is bi himself.I also personally really appreciate Ranli's commitment to delivering both M/M and M/F content with each update, though I can understand why it would bother some players. It really makes the game feel like a Bi game, rather than a straight game with some optional fetish content.
But yes, he takes careful attention that everything is more or less balanced, down to the number of characters per branch. So much that, when he remastered season 1 at some point, to make it nicer, he added the m/m version of the first two scenes (the infirmary and the encounter on the corridor) because it was the only part that didn't have that choice. After that, there have been only a couple of updates, I think, with just a straight or just a gay scene.
Of course, I can imagine that for some people a 50/50 game is basically a full gay game