Because there's too much set-up:
The conflict between Don King and Caesar over Jillian
Don's over confidence, ordering the battle to be broadcast to everyone
Parson's being reinstated as Chief Warlord as a major turning point for GK
Trammenis' overconfidence, and Don King's confidence in him
It all adds up to a big sucker punch to the gut coming up.
There has been too much
It's too obvious.
a sucker punch to who? the RCC or the Parson fanboys?
A loss here could result in the capture of Wanda, the creation of the Queen of the Undead if she croaks and auto-decrypts, or at least a major split with Stanley for using losing the army. GK is too big to be reduced to one city in quick succession, but Parson would be forced to become a field commander. Enough plot for you?
If things go badly for JS then Caesar will think that he has an opportunity to rally support among the Warlords and overthrow Don. OTOH if it goes well, Caesar must know his turns are numbered as CWL and he has to make a move soon.
Don wants Caesar to take a run at him. Why?
Just demoting or disbanding him costs loyalty of the other WLs.
He wants to see who sides with Caesar so he can deal with them too and have a completely loyal inner circle when the new heir pops.
Bunny is the key here, whichever one she sides with will come out on top.
One unrelated point. Parson will still have to account for Jillian in his plans until she passes a point of no return from Spacerock. He doesn't know for sure she won't be back until she is out of range.