Class B excursions (descending below Class B airspace on approach) have been getting quite a lot of attention in the US. KLAX (and KSFO, NYC airports, KORD among others) has been identified as a threat because of close proximity of general aviation aircraft.
GA aircraft, I have been told, have avionics that can tell them in great detail where exactly they are in relation to Class B airspace, so they are more confident in using the airspace allotted to them which puts them in closer proximity to the boundaries of, but not in, Class B airspace.
One way to ensure we remain in Class B airspace is to follow published approach altitudes.
As for the OP, you were correct in advocating complying with published altitudes until the GS intercept altitude. Next time you can, gently, teach that ole dog a new trick.