Probably did take 5 minutes...but a lot of the time in a PPC campaign, keyword selection is a much more important factor than the site itself (as long as the site performs the key action - in this case taking the lead details).
Tbh though, he might be able to improve conversion rates with a more attractive design with the same content but then again if it's already converting sufficiently...
Also check out the copyright date (2001) and the domain reg date (2003). Possibly an offline business he's taken online or swapped domains? Also, checking archive.org shows that the landing page hasn't changed since 2003.
So the options are it either converts well enough that he's more concerned with keyword research, or that he's simply forgot he's running a small Adwords campaign for it. However, some deeper research shows he's got 1.5k+ adwords keywords running and his cpc is fairly high, so that suggests that it's not a mistake.
Conclusion: it converts well enough and has done since 2003 so fair play to him. Although it does it make feel a little ill as I like my sites the cutting edge of design!