"Then just don't kiss publicly". Sure, hiding one's sexuality isn't that hard, especially for a short period of time. But that's the whole problem: they shouldn't have to hide it in the first place.
Home people might know you, but in home country you are against only bigoted individuals, not the entire state.
Objectively, will a python conference attended by an African be more dangerous than that person's everyday life? No. But that's not what it's about. What this is about is PSF's having no tolerance for places that are breaking human rights. And if you want to be part of that community and enjoy its perks, you have to adhere to cultural standards that PSF perceives are essential.