I think the point Stuffer is trying to make is that Omega doesn't "approve" of snorkeling or diving with a Speedmaster. The watch IS rated for 50m water resistance - of STATIC pressure, but it is not rated at 50m for long-term underwater use -
like when diving or Snorkeling. SNORKEL !!
Sometimes 50m != 50m
;-)
The speedmaster is water-resistant which basically means it's able to resist the penetration of water to some degree but not entirely, while a seamaster was conceived to be waterproof and actually says so on the caseback : high pressure waterproof.