In this context, he’s exactly wrong. Have you read the GAO Report? The law in question is the Impoundment Control Act which has been on the books for nearly 50 years. Trump may not have signed it and he may not like it, but his administration is bound by it.
So many voting systems are so easily hackable and so many people have an interest in the outcome that it’s essentially impossible that systems haven’t been hacked.
So the guy who has been giving legal opinions for months that are the complete opposite of everything he was on the record for before, is in fact going to be directly representing the person he’s been defending against all reason on TV. At least he isn’t going to be able to pretend to give his impartial legal opinion on TV anymore.
I didn’t read the GAO report, but the boundaries of the Executive’s authority aren’t well defined because it hasn’t been extensively litigated, so I suspect there may be a reasonable argument that the law is Unconstitutional, but like I said, I haven’t looked at any of this.