This is pointlessly pedantic. In this context the term is being used to refer to unmetered and uncapped bandwidth and that usage is well understood.
I'd agree if the upper bound of unmetered and uncapped bandwidth were so far in excess of the possible upper bound for this application that it were silly to consider - but, like I addressed in my comment, it's very much not.
If he were only talking about meters or caps, then that would therefore make his point a bit of a non sequitur in the context of an argument about whether tarpitting/blackholing a connection is risky for the serving party.
(FWIW, at past companies I've not-infrequently encountered network saturation even without an artificial cap from whomever we were peering with.)
Genuine unmetered/unlimited bandwidth claims also include a port speed. And the really good claims will include a 'minimum sustained' rate (with well connected peers), which lets you complain when you can't get decent throughput because all the servers on the 10G switch share a t1 out to the local internet exchange.
(a) may not be that much, in reality, depending on how their network is set up, and how much other traffic there is at any given moment. It also depends where you're routing to, whether e.g. (i) your neighbour or (ii) a DC across the world (neither is clearly better, it all depends). You have to think of it through the lens of physics and information theory, rather than law and business models.