Buy-back of UNI should be the default case for the treasury. I see no value in turning on the fee-switch to grow the treasury pot without using incoming funds for anything other than strengthening the treasury and extending the operational runway for the DAO. Maybe an additional % is burned to provide some positive price pressure on the UNI token itself.
Actual implementation of doing that is another thing entirely however.
As for the fears about SEC and hostile crypto regulation: quite frankly, not my problem. Im not a US resident, and I dont care what the SEC thinks of UNI. If crypto and DAO structures are supposed to be as decentralized and resilient against state intervention as we all keep saying it is, then we meet regulation head on.
As for UniLabs, an SEC investigation if the community turns on the fee-switch is a UniLabs problem. Not the DAOs. We can of course (and should) vote to use treasury funds to support Unilabs in the event of such litigation.