If I misheard "ABC 1234 TCAS climb" as "ABC 1237 request climb" (and I think that could be most easily done), I would come back with "negative maintain niner thousand"...
Good point. In the scenario we had, the communication was good, and the call wasn't mis-heard, we were approaching to land as well so a request for climb wouldn't have been what the controller was expecting either. I imagine that if we were depating and the controller had an expectation of us wanting further climb, then what you suggest is quite likely. The correct terminology for us is still "abc 1234 TCAS climb" ....maybe it will change soon to align with ICAO.