• Being offended by somebody "calling themselves straight" is stupid and fragile.

• Being "proud of being straight because somebody else is proud of being queer" is stupid and fragile.

• Being "content with being straight and wanting to label yourself as such in an environment where that makes sense" is reasonable.

I dont play the game so I dont know the context but I assume labeling yourself straight does not make sense in a fishing game and as such it is most likely about the second point