Given that Rob Pike seems to think having a shell script that uses tar is better than having a `-r` flag for cp [1], I wouldn't give much weight to his philosophy of programming :P.
Isn't Facebook already censored and guarded strictly? And you won't have wild free parts for grownups if you let the government legislate against "trolls" and "bigots" on the internet. Today they'll just force Facebook into removing "harmful" content but you are incredibly naive if you think they'll stop there.
I hate their usage of 'troll' too. To me, 'troll' means a guy who argues about 0.9 bar not equaling 1 in a math forum. I have no idea what the hell these people mean when they say 'troll'.
All those points apply to XMPP too, and it's way easier to set up Prosody on a server. Are there any specific reasons why you think Matrix is the next IRC and not XMPP?
[1]: https://wiki.c2.com/?WhatIsNotInPlanNine