After letting the engine sit on the position for long enough, it eventually comes up with an even stronger line: Rdf1. Not going into the forcing line with checks turns out to be better, because black can’t deal with the pressure anyway, so white has time to add another attacker before moving ahead. Even with this “extra” move for black before the forcing moves come in, …Ke7 immediately is too late, mate is inevitable.

Prime example of an engine move, I don’t think many people would come up with it, especially since the position is already crushing.