It is too early to discuss about Proof of Bandwith don't you think that. The world is still struggling to get 5G infrastructure and you are discussing about 6G.
I guess he meant something faster than the 5G, if such speed is possible with his mesh network, why not? And ofcourse it has to be be very safe to use.
I think this is not the right time to jump into anything new until global pandemic situation gets resolved.
What if I told you that something like that can help lessen the problems of pandamics and other problems caused by the way people live today