I think he'd been looking for someone prepared to review it for quite a while. The team was split across Mountain View and Dublin (with Dublin the smaller and very much the junior part), and this was during my initial visit to Mountain View shortly after I joined. I suspect getting me to review it was intended as a kind of hazing of the newbie, but I didn't actually mind it at all since I'm a big fan of code review and considered it comfortably within my competency.
This being SRE most of them had a primary background in system administration with a sideline of programming rather than the other way round as in my case, so writing a big bunch of shell may not have seemed an entirely unnatural choice. Within the context of multi-KLOC shell applications, it was actually pretty well written - I learned quite a bit about shell programming in the process. But of course I can has perl, so I've since forgotten it all again. :)