This is correct for all three tokens.
The only solution I can think of is wrapping but that creates a lot of headaches and I think is detrimental to the main goal (i.e. “pools may serve as an effective alternative distribution channel for yield-generating platforms.”). Wrapping would be better for the LPs but much worse for the people swapping.
So I think the current suggested approach is best. At least for PoolTogether it will provide a meaningfully better experience vs. depositing directly (saves 100k gas). The LPs miss out on the Aave / COMP / POOL tokens but are compensated by getting the UNI tokens. And the Uniswap protocol gets to pilot demand for direct swapping into protocol tokens rather than using protocol UIs… which I think is a really good strategy for Uniswap.