This is happening because the command being run does not specify the full path to the Render executable, so it looks in the system's PATH variable, and the first copy found happens to be in the Maya 2009 installation.
The solution is quite simple, you just need to replace the 'Render' in
-range 1-10 Render -s QB_FRAME_START
with the full path to the `Render' executable where it is installed on the worker, as in
-range 1-10 "C:\Program Files\Autodesk\Maya2012\bin\Render.exe"r -s QB_FRAME_START
and don't forget to enclose the full path in double-quotes due to the space in C:\Program Files.