No one is talking about Chris Watt, 6'3" 322lbs. who was drafted by the Chargers in 2014 and started several games for them before getting ACL to his knee. Its been 2 years since his surgery and claims to be fully healed. If so, he stands as good a chance of backing up Sully as anyone.
Wouldn't the reason be the same as the one given re: Toth? If they haven't signed him, isn't he considered gone?
Having so said, I would still love to find out more about where they both (Watts and Toth) stand but, when they were never signed, there is no reason for the Rams to make a statement of any sort.
You don't announce everyone that applies for a job, just those who make the interview stage. In this case, the tryouts were the resumes and the 90-man roster would be the interviews. We're still a long way from the top 53 who actually get the jobs.
I'm not sure if the practice squad would be the interns as I try to wring this analogy out, but I suspect I was already reaching and will try to quit while I may yet retain any semblance of relevance.