Old school webmasters (perhaps this is redundant phrasing) know that's okay. Back in the day, you'd say "I'll put your animated gif on my site for $500 per month" and if you had a networking forum Cisco or whoever would happily pay that secure in the knowledge that your viewers were in the market for their product.
Lesson: target the content, not the viewer. You know the general demographics of who is engaging positively with the tweet, and you show ads relevant to that group. A small fraction of the viewers need to be logged in for that to work.
