Utterly bemused by the 15% of people who think the OP is being unreasonable.
Men can't ever be mothers. I don't really understand how anyone can dispute this. Yes, I suppose trans men can be mothers, but if you believe that trans men are actually men, then you probably won't want to call them mothers in any case.
Men can be fathers. And apart from being pregnant/giving birth and breastfeeding, I'm absolutely of the view that fathers can do anything that mothers can do. But they cannot actually be mothers.
This is just basic common sense, and I despair of the fact that we even have to have this debate when previous generations would have thought it so obvious.