HEV and vacuum of space

If saturation divers need HEVs to keep the pressure differential of He inside a watch from popping off the crystal during decompression, how did the space worn speedmasters not pop their crystals during decompression when walking the moon or floating about on orbit in vacuum of space?

Is this where the reduced water resistance of a speedy is a benefit by leaking enough to prevent this from happening?

In saturation diving, once "saturated", the helium pressure inside the watch can be many (or several) times the atmospheric pressure of sea level, depending on how deep you dive. In the vacuum case, the highest pressure differential is one atm, that is from one atm on the ground to zero atm in the space.

Because they are leakey???

Although David Scott mentioned his hesalite popped off from his NASA-issued Speedmaster S/N 42, during the 2nd lunar EVA, the incident is not described in the official Apollo 15 mission report...
This "hesalite pop-off" happened to Apollo 16 LMP Charlie Duke during his third lunar EVA and this incident was well described in the official Apollo 16 mission report.
There're even good NASA photographs showing NASA-issued Speedmaster S/N 54 with its missing hesalite at the wrist of Duke during work near the lunar rover...
(photo: NASA)

In space no one can see your screen.

AKA The Ripley Effect

Did not know about Scott’s and Duke’s mishaps with their watches. Incidentally, I was taking my first steps on earth at the exact same time Duke and Young were taking their steps on the Moon.

Helium "pressurization" doesn't occur immediately and that's the problem. The watch (and people) spend more time being saturated than they do being decompressed. Quick enough where the helium that sloowwwly made it's way inside can't escape fast enough and finds a way, destructively sometimes. You can overcome this by making the watch very resilient and able to withstand the helium inside, make it so tight the helium can't get inside in the first place, or install a helium escape valve. A "leaky" watch would make it ideal for saturation use but a terrible watch for a diver or any regular use around water. The Speedmaster isn't a saturation watch but it only has to deal with an atmosphere of pressure in spaceflight. Even then, sometimes things fail.