Keep in mind that #Trump is a spineless follower, so he hardly ever promotes schemes...err...solutions of his own, and this one is no exception.
For better or worse, a significant swath of the public decided that Ukraine isn't worth spending US resources to defend anymore, and long before Trump was elected this trade was cooked up as a compromise to bring them back on board.
Sure, Trump is slimy, but this scheme predated him and has brought him over to wanting to continue Ukraine support.
The alternative was probably weak public support overall.