If I can't answer a question, I should be told so before I start composing an answer. If it becomes unanswerable to me, I should be notified when it is unanswerable.
I composed an answer to How to respond to requests to work "for exposure"?:
Pro bono work exists, as does work for exposure. Several people, some or all of them freelancers, have answered your question on a "for exposure." And sponsorship of open source projects exists; scroll down on this Linux Mint blog entry and see donors who have given money to Linux Mint on a "for exposure" basis.
You might benefit from doing pro bono work if it is done through a responsible group like Taproot (see other search results). But someone who works responsibly won't contact you to do pro bono work; you can contact Taproot if you want, but Taproot isn't going to contact you.
One polite response, albeit one that might not be forceful enough in this case, is "I know some responsible venues for work for exposure, and I can approach them if I want to volunteer for a gig. But only if I come to them. I do not work with clients who come to me and ask for work for exposure."
I clicked on "Post Your Answer", and it said, "This question has been protected; you need 10 reputation on this site to answer it."
If the question was protected before I started answering it, I shouldn't have been given the option of responding it (but gotten a descriptive note). If it was protected while I was composing my answer, that should have been conveyed to me while I was there. Also, I'm guessing that's "10 points and association bonus doesn't count", as it is otherwise a bit odd to display that message when I have 101 rep on freelancing.se.
--UPDATE--
The error message does say "on this site" as noted above, but it doesn't more explicitly say that the association bonus does not count. I only saw the error message immediately after I clicked "Post Your Answer," possibly due to race conditions.
