I will say, there is a difference in a grad transfer who leaves a mid-major school after 3 years versus a guy from an ACC school who wants to transfer. Sounds like Cam wanted to transfer and it just happens that because he redshirted, he's got 2 years left. If he wasn't eligible immediately, it sounds like he probably would've done 1 more year at Pittsburgh.
Also, unlike other situations, the player was NOT recruited by the current coach. That's another factor to think about here. Stallings did not recruit Johnson, unlike a grad transfer who is recruited and developed by a coach, only to bolt on him as a Senior.