Since this one just cam up in another place...
3.3.2 says Pilots with a valid IMC Rating are recommended to add 200ft to the minimum applicable DH/MDH, but with absolute minima of 500ft for a precision approach and 600ft for a non-precision approach.
The COED says 'absolute' means:
1 complete, perfect
2 pure
3 unrestricted, independent
4 not in usual grammatical relation
5 not relative or comparative; unqualified, unconditional
It's pretty clear to me that in the passage above 'absolute' means 'not relative [to the minimum applicable DH/MDH]'. It still appears to be a recommendation.
Additionally, the wording dates from before the days in which any AOM where mandatory for a private flight. The idea that a licence-privilege limitation would appear in the AOM section of the Air Pilot would have been absurd.
Finally, at the risk of seeming even more pedantic than usual, I'd point out that these are DH/MDH calculation, and not 'ceiling minima'. You may have a ceiling lower than this and get in, just as you may well have a higher ceiling but not get visual reference at the DH/MDH.
Single-engine aircraft flown for public transport do have a minimum celing for take-off.