Maybe you should ask Omega's marketing execs. I'm sure they were aware of other brands presence on the moon when they introduced the 3573.
Then it should state that on the caseback, or the first and only omega watch worn on the moon. Its a bit of a liberty on Omegas part to continue using that caseback when everyone knows it's not true.
I think the hardcore speedy fans probably have more dislike of the sapphire than the incorrect wording on the back of the 3573
Do they still use it? I've seen ones where they leave off the "and only" and one of the sections is left blank.
My understanding is that Omega no longer uses "and only"... but in marketing land, things can go nutty again pretty quickly, so who knows what claims will be made in the future. As Darlin' said, don't lose any sleep over it, you'll drive yourself mad fact checking every false claim you see in advertising.