It's been suggested before somewhere. It's not necessarily a bad idea, though I wouldn't use it, but I wouldn't ever self-moderate a thread either.
I don't think this would work very well. It would prevent people from expressing legitimate concerns about your altcoin.
Not really much difference between self-modding a thread. Of course people would abuse it but people can just create their own thread anyway.
Its in the unofficial rules that OPs have the right to create a set of rules, and to have those enforced. If the OP in an altcoin thread doesn't want some users to post in their thread, then they have that right to a peaceful discussion. Self moderated threads and deleting posts as an OP just makes the trolls madder and post more often, as soon as they get notifications that their previous posts were deleted.
26. Local thread rules, if stated properly when the thread was started, specific enough and don't conflict with the forum rules, have to be followed.[e]