Pedantic comments follow. Probably best to just skip this one.
Not a non sequitur. You're misinterpreting the argument.
"Because" indicates that what follows ("there's nothing there") is a premise and that what preceded ("Comey won't incriminate Trump in anything") the conclusion. Hence, Busta's argument is the following:
1) There's nothing there.
2) So, Comey won't incriminate Trump in anything.
Clearly, this isn't a non sequitur. The primary problem, rather, is that the argument depends on an unsupported premise. Evidently we have to take Busta's word for it that Trump has done nothing illegal.
(It is also an invalid argument, since the premise could be true and the conclusion false -- Comey could lie, after all. Nonetheless, I wouldn't call it a non sequitur, since the premise gives some evidence for the conclusion.)