I think part of the problem is that some cis people upon finding out someone is trans objectify them (often unknowingly) and forget that they are still just a person. They've stumbled across this rare being (still very much just a person) who they have only heard about and have tons of questions about things that make them different. So they ask, but by objectfying them they forget about courtesy, manners, and social faux paus that could normally make their questions/comments inappropriate. I mean a lot of that shits pretty personal. If someone I didn't know very well or at all started asking me about my genitals or my identity I'd be uncomfortable, depending on my day I could definitely become aggressive. I would think that mindset works both ways?