Granted he's deregistered his membership from the SNP etc, but does that cease your title for a career you've carved all your life? Personally, I don't think so. He's still a politician.
But taking your tact, if he's a private citizen, then he should have funded it himself, like any normal citizen...I find it absolutely pathetic he asked people to support his own cause. Doesn't say much for those who backed him (regardless of outcome).