I think this is a gap in what trivial means here. Some people deploy significant compute to attempt to find exotic lines. I believe most in the chess community would concur that if a human, apparently more or less unassisted, found a line to beat it in their first day of attempts, then finding a line is trivial.

It also is not clear to me they didn’t just stop playing once they had +5, letting the clock expire, seeing as the opponent has no feelings or expectation of fair play. The game is detectably over at that point.