Ryan Grim speculates it's because he has the ear of "his friend Joe" and believes that Biden is helping him push stuff for domestic issues. Thus, he doesn't want to break that relationship.
If this is really the case and it's not because the CIA threatened to give the heart attack gun another try, then this is just absolutely the most perfect encapsulation of socdem politics to ever exist
I can't imagine that they even try differentiating. They'll shoot everything that moves, then they'll bomb everything that doesn't.