I think he’s just implying they have more competence than the FBI in finding alleged missing emails. His comms is very non literal -and people take him literally. His whole campaign was off hand blue collar jokey remarks.
Pundits understood him literally, so they failed to understand him at all. His nomination competitors also saw him in this light and ultimately failed. Mostly, J think they failed to understand his communication style1[1]. Occasio on the Dem side uses some of this same comms style for the left and it works to a degree, but the left is more uptight about being PC in comms so cant go as far afield with it.
Kerry undermining foreign policy is closer to treason but no one bothers cuz he’s an old hand. Let’s say the Dems win the next cycle, but then as they try working with Russia or Iran on things, Bolton struts in on visits to give his two cents...
Basically, I think many people try using a standard/traditional comms framework to parse his comms, but he uses a different more blue collar style[2]. Not frat style of a GWB, or the ancient oratorical style of Obama.
Obviously people are disagreeing with me, but I'd suggest reading what some linguists and political theorists have to say.
[1]https://www.sciencedirect.com/science/article/pii/S019188691...
[2]https://www.journals.uchicago.edu/doi/abs/10.14318/hau6.2.00...