It is called balance of power game. India balances China. Pakistan balances India.
If the Pakistani army supports this game it reflects some or all of the following
1. Fear of all out American support for India
2. Maybe the Pakistani army is bargaining with USA to limit American support for India to the minimum
3. Dislike/Mistrust of China
4. Limitations in China's support for Pakistan
5. Fear of India -- They are afraid of growing differential in strength versus India
On PDF CPEC was called a game changer. Unless Pakistan made peace with India CPEC had zero chance of becoming that. It was upgrade in infrastructure with most of the benefits going to China. I do not think Pakistan had a choice here
For all those PDFers mad at the Pakistani army you can play only with the cards given to you, not the ones you wish you had