It’s not like the passenger knew they were non-critical. I certainly wouldn’t have wanted him to stay silent only for it to turn out they were critical. They also wouldn’t unboard and inspect a plane just on the insistence of one passenger, they’d deplane that one passenger if anything. The fact that they did do an additional inspection implies that safe or not, those missing bolts were not noticed in the initial inspection, which leads one to wondering if they missed anything else.