The problem with mandating PC1 for hostile congested is that the aircraft performance and profile only represent part of the whole PC1 requirement. The other part relates to the HLS environment. I'm happy to be corrected here, but my understanding has been that there are requirements for the obstacle environment to fulfil PC1 to enable a successful flyaway post TDP. Elevated HLSs should, in theory, be ok (might depend on direction, natch), but a ground level HLS probably doesn't meet the requirements unless it has significant areas of wide open space.
This does beg the question as to why PC1 is required by the CAA, but in reality cannot actually be fulfilled. As an aside, does HEMS have a similar requirement?