I doubt that they would have more than that too - although it would make an interesting case study :)
But I also assumed that no one would have more unique nodes than would fit in a standard int either. I think the problem with encoding "node names" as numbers is that David is saying he doesn't think people will want to administer the nodes as numbers, rather he preferes a string derived from the hostname and domain (out of interest David how do you propose to deal with multiple nodes on the same machine, plus remember that for TS these node names are sticky per instance you want to recover).