I remember watching a Hickey talk where I think I recall him saying it was even before 2011, but the exact name escapes me at the moment. However, I was able to find this snippet from 2011:
Fogus: Clojure was once in parallel development on both the JVM and the CLR, why did you eventually decide to focus in on the former?
Hickey: I got tired of doing everything twice, and wanted instead to do twice as much.
Years before the first release of Clojure, Rich used to maintain a parallel build of Clojure for both platforms before concentrating on the JVM; but that is ancient history, and isn't relevant to ClojureCLR today.
ClojureCLR is a port maintained by David Miller, Rich doesn't work on it, so it isn't surprising that he hasn't made any comments about it.
Though it is true that the CLR implementation has much less adoption than the JVM or JS implementations.
For at least a few years now.
I remember watching a Hickey talk where I think I recall him saying it was even before 2011, but the exact name escapes me at the moment. However, I was able to find this snippet from 2011:
Fogus: Clojure was once in parallel development on both the JVM and the CLR, why did you eventually decide to focus in on the former?
Hickey: I got tired of doing everything twice, and wanted instead to do twice as much.
http://codequarterly.com/2011/rich-hickey/