I have the new Bespin expansion, thus the companions, and I see that the Junk Droid is used by the new Tinkerers, and the Cam Droid is only a campaign reward...I don't actually see any way to use the R5 Astromech.

Is this just put in the set for future expansions that might use it?

The R5 is awarded with a tier 2 item card

R5 Astromech is gained from an item card, and Cam Droid from a reward card (Murne Rin's mission).