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.
In addition to hilariousetc's reply, bounty managers are pretty wise as well, they know that they will only get few participants if they put at least 2 merit requirements and I don't think that bounty managers with agree with that. As we can see, they actually doesn't care about the posts quality of their participants because what important for them is their project is getting advertised the way they like.
So, even though theymos doesn't want to restrict Jr. Members, we still need to force to implement the "atleast 5 merits requirements to rank up to Jr. Member and also remove signature from Jr. Members" for the sake of Bitcointalk, or else things will get worse.
We're running out of options.