He doesn;t take the two shortcuts. If you take them both on the first lap then you won;t see him again for the entire race.
Also you can bump the difficulty down to easy. Sure it's a hit to your pride, but that's better than having the entire purchase be a waste.
I know of three shortcuts but I can't do any of them reliably. The first one after the Piranha plants I've never been able to make the jump for. The second one is okay but I think I need to have boost to get there, and I can't do that with all the beakers. The third one is real dodgy in general, though I've made it once or twice in time trials.
I was going to drop the difficulty but it turns out you can't without starting an entirely new save. I might do that later but right now the idea of losing the progress I've made hurts.