I do not foresee HN implementing ActivityPub regardless of a poll outcome. If Daniel and team were look at a poll result it would be a poll built into HN which requires a bit more karma to create. External polls are easier to game. [1] HN already gets too much spam on a daily basis. ActivityPub would amplify that and the the gateway/API itself would likely get shadow-banned the same day in my opinion.

[1] - https://news.ycombinator.com/newpoll