Stewart, assuming he is still in school, is on scholarship for the 2014-2015 year. We're still in that year.

Spring practice does not start a new year for scholarships. That will be the start of the fall semester.

So there probably is no NCAA rule that Stewart cannot work out in spring ball. The other players you mention however, are long gone from the team so the situation is very different.

Players don't need to be on scholarship to participate in spring ball. The rules aren't so much for spring practice, they are for game participation. Spring practice is not a game.