He's correct that AI can train, but it's not relevant.
(1) The issue is with CoPilot outputting copyrighted code AND attaching a separate license to it (looks like it's hiding the initial license and can generate another license automatically). This is reproducing copyrighted code and misrepresenting the license, neither is allowed.
(2) He posted that the output belong to the operator. It's factually wrong. Original copyrighted code belongs to their original writer, not the operator. In effect Github Copilot cannot "launder" license and it is very wrong for their CEO to claim otherwise.
(3) Looks like he's trying to waive responsibility of Github by stating that the developer receiving the code is responsible? Wrong, GitHub is responsible for their actions (vary with the jurisdiction). There's a complex matter of who's responsible when some proprietary code will end up in a company product and they get sued. The company is in violation, they can turn against GitHub for providing copyright code, GitHub was responsible for it. There's a complex chain of responsibility, any lawyer worth their salt would cringe at the claims and responsibility that GitHub is exposing itself to.