Because LevelAttitude's assertion that "the proposed CBM-IR will only be able to be attached to a PPL or a CPL" is incorrect. Read the CRD.
COMMENT RESPONSE DOCUMENT (CRD)
TO NOTICE OF PROPOSED AMENDMENT (NPA) 201116
18. Appendix 6 A.2 — IR(A) Competency-based modular flying training course
Prerequisites
Several comments requested that the competency-based route should also be available for a CPL holder. This was already proposed in the NPA and the Agency confirms the
rating will be kept for both PPL and CPL.
The above seems pretty definitive.
However, having thought about it following bookworm's post, the above only assumes CBM-IR Theorectical Knowledge, whereas, of course, someone who wants an fATPL
will have taken the ATPL TK exams which trump the IR ones.
So, as long as this course is just a means to acheiving a rating called "IR(A)" and not some new-fangled rating called "CBM-IR(A)", then I'm happy to admit I made a mistake
and apologise for any confusion caused.