OP's thesis describe sybil attack, so IMO it's worth to mention those BIP which have few/some correlation.
You're right, I don't know how I skipped over that
I've seen some sources (including it's
paper and Core's developer commentary) mention MuSig improve privacy since outsider can verify signature validity without see used public key.
Do i interpret it wrong or they're talking privacy on different aspect?
I see your point: multi-sig using Musig looks like a 1 input transaction when spending from a Musig address, regardless of how many signers are needed to pass the threshold. But the way I understand it, it's Schnorr's additive keys property that confers that quality, and not Musig per se.
Certainly, Musig is designed at least in part to prevent the attack I described in my previous post, an attack which is a consequence of using additive public keys to generate the public key for a multisig address. So it seems logical that it's Schnorr that's improving multisig privacy, and Musig that mitigates the risks of using Schnorr signing for a multisig address.