My point isn't that an unregulated prediction market (Polymarket non-US markets are non-CFTC certified) can obscure insider trading. My point is that Brent has enough liquidity that an insider can trade without moving markets. There's plenty of insiders that work on a contract basis and aren't required to disclose trades by STOCK Act provisions for public disclosure.
And honestly we aren't even out of the 45 day window around disclosures that would surface any Brent or WTI trades around the current Iran conflict anyway.