Suspicion doesn't mean baseless hypothesis, e.g. "Mars is an orange." The NTSB would never say (and has not said, as you've conceded) it "suspects" the "bolts were never screwed in."
Were there a lack of marks where the bolts should have exerted clamping force, there would be basis for suspicion. That isn't proof. But it's more than a hypothesis.
Suspicion doesn't mean baseless hypothesis, e.g. "Mars is an orange." The NTSB would never say (and has not said, as you've conceded) it "suspects" the "bolts were never screwed in."
Were there a lack of marks where the bolts should have exerted clamping force, there would be basis for suspicion. That isn't proof. But it's more than a hypothesis.