I don't think this is a good solution since it makes delegation slow, but couldn't you work around the flaw by not allowing an NDT to vote until proposalUpdatablePeriodInBlocks + votingDelay + votingPeriod blocks has passed since it was minted? That way you can't swap -> mint -> vote for any prop that is created

I think it can work. So no snapshots, and an NDT can vote only after “maturing” for a prop lifecycle of blocks.
Should an NDT be allowed to vote if the Noun owner has changed? eg mint an NDT and then transfer the Noun

part of verbs team, working on nouns things

Yeah exactly! Allowing NDT to vote after a noun owner change feels like mostly a design choice & not a security concern. I lean towards allowing it for convenience for holders. Maybe worth adding an updatable deny-list in NounsDAODelegation and not allow voting if the noun is owned by a known/common pool?