What do you think? Is checking your Apple Watch any less rude than checking your phone? Do you plan to use your Apple Watch during meals, conversations, meetings, etc? Or are the rules the same, and it's rude to check your Watch at certain times?
No, but it's more discreet.
It still takes your attention away from the present company and shifts it to a gadget. It's just quicker and the person may not notice. Either way, the watch wearer is still being distracted.
It's kind of like when you lust after someone in your heart but your partner doesn't notice. You're still doing the action, and will reap the consequences but they may be different consequences if say you stated out loud that you wanted to have sex with that attractive girl. Either way, the intention was there and the seeds were sown.
Nowadays though usually both or all parties are looking at their phones Constantly anyway.