The nicest thing you can say about Donald Trump is that he's completely mercenary.
He'll turn on a dime if he sees advantage in a position and there's nobody he won't stab in the back given half an opportunity.
Biden is a fixture of US Foreign Policy. Trump is a Wild Card.
I could very easily see Hilary pulling this trigger (or Obama or Bush for that matter).
If anything, I suspect Trump mismanagement of the occupation probably was what opened up diplomacy with Iran wide enough to convince Solemani that a visit was possible. The bombing (of Iraq's own airfield!) was just Trump trying to slam the door shut after the horse had left.