I think in this case, the server parses more than just his page, and more than just his domain, perhaps. This is just his way of "turning it back on" even though the sysadmin for the server that hosts his site has it turned off. Just a guess.

I have sites that have it both ways. btrott has a good point, however: doing it later would also allow you to cache the answers, freeing some (perhaps a lot) of calls to gethostbyaddr. Unless it is a really, really busy page, however, it probably does not hurt too much to look it up each time.