He posted that in six different subreddits, so I guess he think he did.

Dunno if just a troll or something else.

That is the wrist detection. You can decide between getting a cold wrist and always see you watch, roll your sleeve up and down or disable wrist detection.

The latter has some consequences, you´ll lose stuff like Apple Pay (AFAIK you have to set it up completely anew, but I could misremember this), unlocking you Mac, fall detection, background HR, notifications, and some activity tracking features.

Like any other app: via the app list.