I dunno, if you're being really OCD you could give it an oxalic acid bath, but the rust spots look totally superficial, and not at all like 'the bad kind' if you could call it that. If you store it indoors, it'll never get any worse. I would just clean it up and maybe wax it, and regrease/lube where needed. As you point out, it has a nice patina. It would be a shame to start over.