@ Perikles - A c&p invitation reply on a Looking for a clan thread is not against the forums rules, and no action needs to be taken on that user. If he posted it multiple times on your thread, that would be spam. You stated in your opening post "Note all C&P posts will be ... ignored", which you are more than welcome to do, so best to just ignore it, rather than spend time and energy getting upset about it.
The OP was bumping the thread. Even though its been inactive for a little bit of time, the OP has put effort into the thread so I see no reason to have it locked. Grave-bumping is more when a player is bumping a dead thread mainly to cause clutter among active threads.