See the quotes? I was making a sarcastic extreme example of the "innocent joke" excuse.
If someone does something like what happened to you, they should know better. They just can't hide behind "sorry, didn't realize".
I sympathize with your difficulties getting your watch to work, but I think your friend owes you a very expensive dinner, or something similar.
Yes he probably did not know the extent of the harm, because none of the huge tech websites reported any issues with the Apple Watch. I wonder why they said nothing about it, specially that it sold millions already and someone must have reported similar issues.
His friend is a bad troll, we know it but If I was him (and no, when I troll I never harm people), I would just think I am messing around with a friend by "rebooting" his phone, not by bricking his watch.
I remember a few years ago when I had a Nokia with a bluetooth, and there was an app that allowed you to reboot your friend device if they accept the bluetooth connection. I had fun trolling them with it. That's because I was sure it would cause no harm but just a simple reboot.
This should tech Apple a lesson though, which is to include a lightning cable port in future and offer iTunes support so people can restore their Apple Watch the same way they do with their iPhones, or else Apple will be hit with many replacement requests for the Watch if such a bug happens again.