Thanks for writing this, @Don. In general, I agree that there are significant issues with holding so much of the treasury in USDC and USDT, and that these assets carry significant censorship risk. I think we need a strategy for how we can reduce and manage this risk, and I appreciate your raising this topic here.
In my opinion, I’m not sure that converting only a relatively small percentage is the right strategy, and I’m also not sure that the proposed assets are ideal for solving the issue. For example, DAI is mainly collateralized by USDC, and in the event of censorship by Circle, could end in a nightmare scenario in the current configuration. Additionally, USN would have to be bridged, which would expose the treasury to added bridge risk.
Some other possible solutions I can think of might be to use LUSD (which had a really solid proposal here) and RAI (which is one of the most interesting stablecoin projects in the space, but may lack the sufficient liquidity for our needs)…
Another possible solution in this bear market would be to go ahead and convert the existing stables in the treasury to ETH. I think this would send very strong positive vibes to the ETH ecosystem, and be a good long term investment for the DAO, while de-risking away from stablecoin assets that in general feel highly risky right now.
Just my 2 UST for now 
, would love to hear what others thing.