I think, the reason for not giving PR and SG, 130 mps is that, the TT of both trains is such that people board them at night, just have home made carried dinner and sleep at 2200 hrs and when they wake up at around 0600 hrs, get fresh and brush, their destination arrives.
If slack in TT is removed from these trains and 130 MPS is given, the passengers will not have full 8 hrs sleep and reach ald/ muv at 0500 hrs.
Itni jaldi kisiko nahi hai.
As...
more... we can see Pnbe Raj having much slack between DDU and Rjpb, so that it reaches around 0600 hrs at RJPB.
Warna, given to its Priority and MPS, it can easily reach RJPB by 0430 hrs.