Is it possible to set up role based access restrictions to saved search results? The only option I see is to remove the jobs link from the applications. Even then a commercial user could follow a results link back to the saved M&G results or get "lucky".
The saved search should be restricted through the object ACL's. However, if you share a specific link to a search via the "get link to results", you will be able to view those results.
In particular, unless you share them, the saved search results will have the same ACL as the original search object they were generated from.