I know he is not a fan of it, but what made me think he might at least consider it for a second was his own post that I've quoted above and the fact that this is not a real restriction imposed by rank or by something like a merit requirement for a signature.
It is your own choice, you want to do bounty for an ICO on bitcointalk stick to that ....
Besides, the idea was that such a member won't be able to post it certain parts of the forum, he will still be able to read (lol, like bounty hunters are reading anything ...)
We could even have a new sub-forum, the bounty members hang-out, although I wonder who would volunteer to moderate that
The reason why theymos might not be a fan of restrictions because, he had imposed them before, and things didn't work out as they were intended to(newbie jail). And he is a big fan of free speech.
theymos has also said he is open to ideas where non-shitposting members can earn money from this forum:
BTW, if anyone has any ideas for simple things that these ex-nonsense-posters could usefully do to make money, I think that this'd be a good project right now. There are apparently quite a few people who were making money on the forum and could use guidance. Even though their past activities were not good for this forum, I doubt that they are useless in general.
Yeah, I thought it would be might encourage some users to actually read what the topic is about during the cooldown period.
In the end...whatever...I tried ...

Maybe somebody will see this and say, I can do better > theymos impressed > problems solved

The cooldown period is fine, 6-10 minutes gap is fine between posts.