You have made a good point about the impression we may create if we impose restrictions now that the newcomers have arrived. A discrete method might be to alter the cookie such that outbounds are directed to the Probes immediately or to a queue for approval by a MARSupial or Staff Member. I think that any MARSupial should be able to allow a message out. That would then act as an incentive to join the ranks of the MARSupials by demonstrating good posting and participating behaviors.
The bottom line of all of this is that we WANT new people. We NEED new people. We are NOTHING if we are an insular and closed group.
Reasonable precautions against malicious individuals is required, but let's not "throw out the baby with the bath water."