You are all very good at quoting rules and regulations
1. The IMC rating holder is not trained according to the sylabus to fly a precision approach below 500ft. DH or a non-precision approach below 600ft MDH.
Why not? The usual rules apply, if the needle is out by the specified amount of deflection (personal limit / ½ / full scale), you execute a missed approach. I'm sure there are IMCR holders out there capable of flying an ILS down to 20', and IR holders who are not even capable of getting to minimums (because they are out of practice, or can't afford to remain current
).