Thank you for making the most informed post on this thread.
Yes, the man is absolutely right. The question is not about whether the military can do it, trust me, they can. The question is whether it is politically feasible to do it. So let's war game this scenario a bit.
At the moment, MFU is nothing more than a figure head, his organization has become redundant in Pakistan and its Umer Khurasani that has emerged as the greatest threat to Pakistan's internal security. For now, MFU is easily replaceable, we can kill him and the Taliban will have a successor announced before he has bled out.
On the contrary, by breaching Afghanistan's sovereignty so blatantly, we will not only undermine the Afghan regime and energize the Taliban but make the Afghans further weary of our intentions. Add to that the fact that we will set a negative precedent in the region.