had to replace the saddle, so I put a few dabs of flour-emery powder on
the
seat clamp. There was enough grip that I could get hold of the saddle and
twist the post out.

Now re assembled with copper slip anti seize compound.

Nice! But copper?

Copper based anti-seize paste is what they have on the shelves round here.. I
have a tub of something based on a silvery colour metal, but I generally buy
more Copperslip when it gets used up.

molybdenum is a "friction modifier" - I had to do the clamp bolt up
seriously tight with just the copper stuff on it.

This reply does not address the validity - or lack thereof - of the alleged theory of operation of anti-sieze compounds, which says that the metal used therein should match the metal which is having a corrosion problem, so as to be taken up by the reaction and thus spare or partially spare the coated part.