- First, register your private coin to the coordinator. If it's accepted, then there's no Sybil attack.
Step 0: Find private coins outside Wasabi. 
I explained to BlackHatCoiner 3 different ways to confirm that a coordinator is not a bad actor
Your "solutions" don't protect you against a malicious coordinator with sufficient liquidity, filling the coinjoin with his inputs, with variable amounts. This way, de-anonymization can be orders of magnitude more effective, through blockchain heuristics like observing input and output clustering. There is this account in Twitter, wasabistats, which has recorded a bunch of Wasabi coinjoins with an anonymity set delivered to nowhere close of what was advertised in the client. The reason is simple, people consolidate their private coins in such a manner that downgrade the anonymity set. For example, if in a 200 input / output coinjoin, 190 of them belong to a single entity, then de-anonymizing the 10 inputs becomes a much easier process.