I would think it would take many atmospheres to crush the crystal casing considering its size - possibly in the order of 1000.
Possibly, would you be sure that it would be OK to a few hundred?
The reset switch will not be actuated by pressure - it is open
Not necassarily. It's open at the top, the base is a solid piece of plastic with just the legs projecting through. There's a cylindrical well inside with a cup shaped piece of spring steel. (nickel plated). On top of that is a plastic bush that fits quite nicely within that well. It's not designed to be air tight, but could (especially with the addition of a viscous fluid) produce a close enough fit to form a compressible air bubble in there.
Not sure whether the electrolytics have significant voids or not. Other components may also have voids - who knows?
It's not just voids that are a problem. The electrolytes are generally compressible. This could allow sufficient distortion of the can to damage the dielectric. I'd feel more confident with tantalum beads, but even then, with the pressures anticipated, I think a bit of research would be worthwhile.
I doubt anything else on the board would have a problem.