My biggest concern is the question of what is politics? Surely partisan political issues are politics, but is the position of women in tech also politics? Is climate science? I can see good arguments in either direction. The problem, then, is that it places too much power in the hands of those who answer the question of whether something is politics or not.
HN is already pretty bad at silencing opinions outside the groupthink common wisdom; I think this would just make it worse.