I guess what you are trying to say is that it would not falsify the 'fact' of evolution.
But if he was right it would certainly falsify the Neo-Darwinian theory of evolution. In other words, their would need to have another mechanism (or simply an add-on) to Mutations+NS = Evolution.
So no, his argument isn't irrelevant. It is simply saying: ''Yeah, I know you say this evolved into that, but the mechanism you are proposing couldn't have done it''.