It's simply brokers do it all the time subcontract who cares if he don't have the trucks to pull the load he knew that when he was bidding on it that not illegal that jus business
if this guy has a legit brokerage with good credit you have nothing to worry about, and yes he needs the little slip to get paid, but if you factor you get paid right away. People get contracts all the time and sell the freight how do you think all these brokers get the freight? they lie and say they have trucks on trucks on trucks but they do not have crap. If hes just a carrier with no broker authority and you do not know him well or trust him stay clear away.