Here we go again...
In JAAland PICUS is not PIC! Anyone trying to sell herhis PICUS as PIC, stands zero chance at the job interview.
Sole purpose of PICUS is to provide PIC hours towards the 250hr PIC ATPL requirement, for the pilots who started flying as F/O with the airlines before reaching 250hr mark.
Whether only TRIs or any capt. can sign PICUS in logbook, depends on particular company's PICUS trainning programme, which has to be approved by the local CAA.