What about his comment is hostile?

Well, I do believe twitter makes people less intelligent^* which lead to Americans electing Trump (twice even), which eventually impacts me somewhere down the line.

^* Because the focus on short sentence and the engagement algorithms favours highly polarised angry one liners that trigger primal emotion and is a successful assassination of any intelligent discourse.

And I say that having seen the progressive brain rot of my parents after they retired and started doomscrolling on twitter and being bombarded by more and more extreme messages, until it became a constant stream that can be summarised roughly by "brown people = bad".