"To restate Mark's point: Lunar exploration can ride on the coat tails of a manned Mars program. However a manned Mars program can not ride on the coat tails of a manned lunar science program."

It depends on what you mean by the lunar science program. But since a "science program" is not a specific goal and has a tendency to be focused the wrong priority, I guess I would agree.

"Also a manned Mars program is sustainable provided the political will exists for Space Exploration (the real problem). However a manned science base on the Moon even with lots of political will would probably time out after after one-or-two decades."

I see no reason why it would "time out" [given the the same unrealistic political support as a Mars program]. It's not as though there is a shortage of science would could be done on the Moon. And a lunar base which was designed for long term habitation [buried under ground so there it's protected from solar flares and galactic radiation] would last as long as the pyramids. Unlike ISS which if it isn't constantly maintained will de-orbit, and there's always a possiblity that debris could wipe out ISS regardless of how well it's maintained.

"There isn't that much one can do on a low-gravity volatile-free ball of basalt except do radio astronomy on the far side."

There is lots of science which could be done on the Moon. But more importantly there is lots of industry which could be done on the Moon.
Using the Moon as a platform for all kinds of different telescopes is one major near term advantage of the Moon. Another relatively near term advantage of the Moon is building and using mass drivers. First you will have fairly small mass drivers, but since the Moon has a good vacuum, bigger ones can be made, which in the longer term will really open up the solar system to cheap transportation.