When you first set up your Mac, you are asked explicitly whether you want Find My Mac turned on and the Preference to turn it off is then in plain sight in the iCloud preferences. In what way are the two comparable?
Ah, then yes, it seems, and you should be right (at least in principle - I'm not sure, either) with regards to network ports. (I've done some light scanning out of curiosity, but that's only anecdotal...)