In this case, you are going to need to explain the origin of your coins, and im not sure how I would explain I made some BTC posting in some internet forum, this may not be convincing to them even if it's the truth.
But it is the truth.
You should hopefully still be able to prove that you own the account that posted. You'll be able to point to the thread where you signed up. The thread will be there that describes the sig campaign and the pay rates. If you're sensible you'll retain the private key of the address that received the payments and lists each tx.
Screenshot everything now just in case.
People deposit millions in banks from selling art made out of their own sperm and turds. This is less weird by a long way and fully traceable.