Technically, this is not cheating. These paid staffers go into the caucus and give speeches, cajole, lobby, offer "information" (which may, or may not be accurate).
They do not vote.
It is precisely the method that Cruz will employ.
Unseemly as hell, and not in keeping with the spirit of the caucus, but legal.
While I agree with you, I think it's amusing that Clinton would resort to legal technicalities to give her an edge. Once a lawyer, always a lawyer!
On the other hand, if there was some nationally-recognized supporter from outside the state, what's the harm in having them endorse you?