but i think the solution where managers make restriction for Junior Member to join any campaign is a great idea too or at least making a minimal merit requirement for Junior Member to join a campaign.

I personally think that bounty managers should just implement a merit requirement into their campaigns, requiring Jr members to have at least 1-2 merit to participate. Realistically Theymos isn't likely to restrict Jr. members further otherwise he would have done it already, so the bounty managers need to be the ones to curb this crap.