Because Imran Khan has been told of the economic consequences for Pakistan should Pakistan not accommodate the American requests at least to some extent. Except for some level of assistance from China--which will be a paltry amount and I won't blame the Chinese for that--the richer countries of the world would punish Pakistan: From GCC to EU to the West to Japan/S. Korea.. etc etc.
The economy of Pakistan has been the Achilles Heel (or Achilles Hell!) for decades. Militarily, Pakistan is not as weak as it was on 9/11 when it had to kneel to America and America is a greatly depleted country anyone than those days. But Pakistan is on a path of a fragile economic recovery-- "fragile" is the right word. $issing off dozens of powerful and rich in an alliance with each other countries would be only possible IF/WHEN China had Pakistan's back to the fullest OR Pakistanis would be willing to eat the proverbial grass (a la North Korea).
I predict a secret deal with America to accommodate the American requests to some extent. No concessions like after 9/11 but something acceptable in a quid-pro-quo likely.
BTW, chest thumping will lead to another Qaddafi or Al-Assad or Saddam like fate for Pakistan. EVEN the Iranians don't do knee jerk reactions. Thank God the Pakistani planners are more pragmatic than this forum.