Does monero have the liquidity to absorb all that price action and still keep him anon? If privacy is about hiding in a crowd, monero seems like a small crowd. Maybe he'd be better off with a coinjoin (of multiple coinjoin pools) into a submarine swap on lightning. Taking into consideration denominations and all that of course. Then probably sell for cash or gold on the p2p market.

That all being said, with a big enough amount of money, no technique will keep you safe. If the IRS sees lots of new fancy toys, they're gonna swarm every aspect of your life with investigators.