I highly doubt this. First off America is not like Qatar where they are so desperate for athletes that they hand out makaratasi like old newspapers.
Second, Bett has not proven his consistency yet. For all we know he could be a one hit wonder. Heck he did not even participate in the Diamond league.
Third, the US can top the medal standings without buying runners. They don't come begging runners to defect. It is usually the case that runners are desperate to defect to the US: Lagat, Khannouchi and now Robert Cheserek who may run for them in Rio.