I'm honestly having a hard time picturing what kind of discussion or brainstorming could be had around the statement in said comment. "It might be useful to have more smart people working in [popular field]" in the context of "look at this smart person" is just... unactionable?
Further, it is unclear what the link to a conference is supposed to add - is this actually an attempt to get said mathematician to completely switch fields on a whim? Based on a HN comment? That's just uncalled for... Or is it trying to recruit random HN readers? In that case, how is this at all related to the topic?
Like in any group of humans, it takes a certain perspective and tone to communicate your ideas effectively - doubly so if you want to engage in "new ways of thinking" with others. The comment in question is lacking that (in my - subjective - eyes). I don't think "I wonder if" is misplaced on HN, but I would concur that (as you hinted at) a certain way of articulation is rewarded.