We are procedurally in violent agreement. Nonetheless, the G/S is not
primary prior to the PFAF, any minimum altitude constraints
notwithstanding. That is the legalese of Part 97. I am just the messenger.

We're agreed that at SCK following the glide slope down from the 2000
foot vector altitude is the best procedure. We're also agreed that the
G/S is not primary outside the PFAF. Instead, one must abide by the
published altitudes - in this case we must remain above 1800 until this
PFAF. At SCK, this is logically guaranteed by our "best procedure".

However, I detect that your position is still that some sufficiently
zealous FAA inspector could violate me for using the G/S to descend to
1800. (otherwise how could the new instructor be "technically
correct"?). I disagree. If that is your position, please cite which
verse of Part 97 that this zealous inspector could attempt to violate
me on? Which regulation does our agreed best procedure not comply
with?

It's pointless discussing legality without reference to the law.