> simply asking to justify or explain their claims may be perceived as an attack

I think that's because that often is a prelude to an attack.

I know someone who mainly asks for explanations or justifications when they're getting angry about something (and it's obvious). There's high chance the next thing that will happen is some kind of outburst (or quiet seething resentment). With them, the question "why did you do X?" almost never has any element of curiosity to it.