The GDC / Q&A does not care how you use a COTS part (within reason of course). You are fully allowed to use the 3rd CIM slot in any way you want, as per the designed use or otherwise. There is not even remotely a legality issue regarding a situation like this.
If by valid you mean:
Legal, Yes
Useful, Yes
Seems like a cool unique solution to a mounting question!
I’m pretty sure it was a joke 
Yeah, it was a joke, sorry. Shoulda put a winky face
By the way, I’m a software guy, so if there actually is something obviously mechanically wrong, I wouldn’t know ::safety::
Why did you choose the AM motor over a more powerful motor, like a 500, 775, miniCIM, or CIM motor. Worried about current draw?
The AM motor in question is the AM-2161, AKA the 775-5. Plenty of power for what we’re using it for, but the driving design factor was actually speed. The 775-5 has a free speed of 5700rpm…and that’s attached to a 100:1 VersaPlanetary with an 18t gear on it, driving a 24t gear which drives an 18t pulley which drives a 60t pulley…total reduction of 444:1. Didn’t want to go with something with a 16000 rpm free speed.
And yes, we are aware of the torque ratings for the versaplanetary and are well within limits.
I just realized that the motor wasn’t part of the drivetrain. Woh. This is awesome.
Very cool space saving design by using the extra slot on the 3 CIM gear box. I love it.
Where are the mecanums?
It was getting toward the end of the meeting and I was too lazy to… um… “put one back on”
+1