SWR has to give priority because being single line section in HVR UBL, if this train is not taken before 10.15pm, then it will act as bottleneck for all trains departing UBL after 10pm towards SBC.
For ensuring no incoming trains at UBL after 10.15 pm, this arrangement is made so that KSK, RC, GG, BGM can have smooth run upto HVR