@evan@cosocial.ca @alice@lgbtqia.space Evan, I know I'm piling on here, but seriously.
It should be obvious to you that you can't *tell* if people don't want their content boosted without *asking* them. This is what "informed consent" means.
You strike me as someone who thinks you can solve social problems with tech, but this isn't true (and never really has been).
If you want to both let people know your services (which, tbh, I'm not sure I see the point of, but you do you) exist *and* actually get consent, the correct flow would be:
If the account in question has not been seen by your service before, *reply to the post you want to boost, asking for consent to boost it, fully explaining what tags.pub is*. Store and respect the response, and allow a mechanism for opting out in future.
(Ideally, you should also allow the response to be "for that one post", "for only these tags", or other limiting selections, not just "opt in for everything".)
Doing anything else isn't opt-in, it's opt-out, and deeply disrespectful of social contracts. Saying that consent matters when you clearly haven't considered *just asking* shows you have no real understanding of what consent (or a social contract) is.