It was a 'silly' shot. To be honest his 2 hander isn't very strong and he'd have sliced in general for that pt.
Some other players I have seen use a 1 handed topspin pass on occasion, usually as a last resort and sometimes even successfully - Tsonga and Nishikori come to mind.
Tsonga's is actually quite decent, and surprising and you'd think had it learned to use it properly what a good shot it could be!
Kei has hit some surprising ones too considering his already solid 2 handed backhand. Again very much end range stuff.
Doing it to 1HBH players isn't very nice