I am not sure if ETSI gives any such clear outline for KPIs.Its upto you. From subscriber point of view SD _Blocking does effect CSSR so should be included. And since RACH_Request breakdown is not available so precise SD_blocked for Call_Setup cannot be measured so accurate CSSR with SD_Blocking is not possible.
Its a give and take situation. I prefer to include SD_Bloking in the formula as it gives a getter KPI and helps issue identification