Well, he has a point.
In this case, you can always 'ring up' his upstream provider, who can
either turn off the whole connection or block the offending host(s). Or
your upstream provider.
I don't see this as being much different from "no-support" dialin services.
They may not be manned at all. Most ISP's are planning for unmanned POP's.
It might not be all that long before we have providers with near total
lights out except for bean counters and maintenance people who replace
failed parts in fault tolerant equipment now and then. Some might say we
have that now Many places aren't 24 hour, and 24 hour staff doesn't
really buy all that much if the Noc operators can't make changes anyway.
So what use is a phone number?
Indeed, I recall that not so long ago people talked about taking contacts
away completely to prevent them from being used 'inappropriately', which I
think they meant as 'contact info is public to other NOC's only, and only
for NOC use, not customer support or anything else'
What people should really start thinking about is automated systems to do
these things, and authentication/trust relationships for other Nocs to make
changes and some kind of penalty for abuse of that system.