Is there any risk these teachers are going to report to the district? I very much agree with HKs suggestions re checking in with the principle (and whoever else) regularly and putting this issues in terms of "How would you like us to discuss his with staff?" "Is there somewhere we might cause less disruption?"
Now that its not a secret the principle possibly needs to address gossip head on in a staff meeting, but they'll want to think that's their idea (and of course they need to know its an issue).
