So, a 6 input, 6 output coinjoin with variable amounts would look like this:
0.50 BTC 0.50 BTC
0.40 BTC 0.40 BTC
0.30 BTC -> 0.30 BTC
0.20 BTC 0.20 BTC
0.10 BTC 0.10 BTC
0.05 BTC 0.05 BTC
It would look nothing like this, refer to the actual mainnet coinjoin I posted.
since we're talking about the case where most of these hundreds of inputs are disguised as anonymity set, but are maliciously added by the coordinator (which is theirs).
No, we're not talking about this case since Boltzmann score has absolutely nothing to do with Sybil attacks.
Therefore, if we know beforehand that Alice controls only the 0.10 TXI, we could ignore certain outputs (in this case all the other outputs).
But you don't know that information

I join, my coins pass the coordinator's approval, my friend's coins are refused. Why is this considered Sybil attack and it's not my friend's coins "naughty" according to blockchain analysis?
Ta da! By asking your friend to register their coins, you've revealed the coordinator is trying to Sybil attack you
