Not only that, but you could probably make 50 posts per week writing the kinds of posts OP wrote. Members do what Google+ did in campaign threads all the time (at least they were doing it before I put the Services section on ignore, but I'm assuming things haven't changed much). It's not worth your time and effort to respond to an application, even if the campaign is clearly closed, the member isn't qualified, etc. They're probably not going to read what you write anyway.
I wouldn't rule out that all candidates won't read at all. Maybe they'd re-visit that thread, scroll down and see someone or a bunch of participants quoting them.
Nowadays, some campaign managers (including one managing the sig campaign I'm in) are not counting
the posts made by the participants on those threads.
Good move, I'd say.