You are correct. Robert Young was SOTM in 1995.
After watching TCM awhile, I've noticed certain stars get every tribute possible handed to them on a silver platter while others get no love at all. I was actually shocked Robert Young never got honored with a SUTS day. (Like you, I'd like to see Young's films, which he made before starring on Father Knows Best.) What's worse is Young has never had a birthday tribute on TCM because his birthday falls during 31 Days of Oscar. (His birthday is February 22nd.) The "popular kids" (John Wayne, Cary Grant, etc) of TCM should move aside once in awhile.
Yes, I think this is how some stars get forgotten. It's not right.