My only thought is 'RCSPAST' is the joke, but I still don't get it.

Edit: I think maybe Don's reputation as an in-space inventor (first patent for something invented in space) means the clock spring device got a long and contrived name for it's quite basic function.

I think its just them being overly technical on the naming the mechanism, ie "Rotational Coil Spring Powered", rather than just being a plain ol Windup Star Tracker