I don't see any issue with you trying to SDC on the return but I wouldn't attempt it until you are in RNO. You can get an idea of what's available by booking a dummy flight on delta.com ahead of time and then calling and asking.

As far as not making the SLC-RNO flight, I would ask about just flying right back to ATL and asking for ORC. I got ORC earlier this year on that mistake B fare, MSP-SEA-EAT-SEA-MSP, as did a lot of other FTers after our AS flight couldn't land in EAT due to visibility issues. We all jumped on the first flights out of SEA back to MSP the following morning. I got my ORC and I know of one other FTer who got his and I would assume everyone else did as well. In fact, other people mentioned that it had happened on other attempts into EAT and that they got it for those flights.

I did two of those flights but others had booked as many as 8 of them. I believe at least 3 of those never made it to EAT and I saw no rumblings in the MR forum thread for that fare about not receiving ORC. BTW, all of the SEA-EAT-SEA flights were on AS.