I think this may account for the JLC recommendation in the manual against diving and other water sports. In any case, I found it interesting, so thank you.
Would you be similarly concerned about allowing a watch with 100m WR, a screw-down crown, and a chrono pusher get wet? As I understand it, most screw-down pushers merely lock the button to prevent compression, but do not accomplish any further WR protection. The example I'm thinking of is my MIH watch, which I plan to wear for most everything, including any swimming, fishing and beach activities. Any reason to be concerned about the 100m WR of that watch in those circumstances given the mono-pusher chrono?
Cheers,
Daniel