Like I haven't run Coq but I assume that in this particular instance, the answer is a rather trivial "yes"? You'd think about, creating this proof is a gigantic research slog and publishable result; verifying it is just looking at the notes you wrote down about what worked (this turing machine doesn't halt and here's the input and here's the repetitive sequence it generates, that turing machine always halts and here's the way we proved it...).
But taken more generally, not for this specific instance, your question is actually a Millenium Prize problem worth a million dollars.
In principle, you could reduce the problem into running a few very costly programs, so that the proof is completely verified as soon as someone eats that cost. (Some 6-state machines are already looking like they'll take a galactic cost to prove, and others will take a cost just barely within reason.) But this definitely isn't the case for the BB(5) project.