Some of it is him not being in race condition. You can train all day and never replicate the toll that race day takes on these guys due to increased heart rate on the line, spiked adrenaline, deteriorating track, crowded first corners, etc, etc.
The other portion of it is probably him not mentally being “over” the recent incidents he’s had. It takes time for a lot of guys, this is scary stuff.
At the end of the day we’re talking about a guy who was the fastest amateur in his age range growing up, came back from 5 broken vertebrae to win a 250 title in his 3rd year, and just last season won multiple 450 races and his first ever OA. He will be just fine in my opinion.