If I create an NFT by setting mintAuthority to null and foregoing a metaplex Master Edition, I retain the ability to arbitrarily freeze and thaw NFTs so long as I retain freezeAuthority on the token (and no one else can change that). I've used this to various effects so far.
If I instead set a Master Edition on the token, I can only freeze it if I am the delegate of - I believe - the associated token account I mint the NFT to. And - I believe - I cannot set the delegate of that account without its owner's signature, which I do not have.
I understand that an existing NFT owner can delegate freeze authority to someone (e.g. escrowless marketplace contract), but I don't see a way to do this as part of an airdrop.