> work which is coordinated to a “9-5” office workday and that will be harder to change than a clock.

[citation needed]

Isn't 9-5 already a reaction to DST? At least here in Germany, office and school hours used to start at 8 or even before that. Stores also used to open at 8. Nowadays, most of that has slipped to later times, many stores only open at 10 now. And people work longer. There is also discussion, to shift school times to later.

If we just to back to standard time, it is easy to go back to the "old" times once and stay there forever.

This is probably the root of the disagreement. I'm pretty confident 9-5 is easier to change than the existence of DST.