If you exclude newbies, you will be ended up with less than 50 participants in your campaign. Wait, actually, I should lower the number. I can't remember if I have seen a few Jr Member or above in a social media bounty. Will this rule be applied for every bounty managers? Actually, will it be a forum rule? No. Then any bounty manager who will allow newbies participation will be picked by the project. You of course know how bounty management is working these days. Most of campaign managers are newbies or Jr member with no history of managing bounty but still getting campaign because of their charge.
What do you think if there's a new rule that newbies won't allow to run bounty campaigns and also there are merit and rank requirements the same as the bounty participants?
Rule from the forum? I don't think it's going to happen. Also, management doesn't necessarily depend on rank though I agree that having a high rank CM is advantage for the project in numerous ways.