Head coach Jim Caldwell indicated that Thornton, whose six-game suspension ended after Sunday's game, isn't guaranteed to be added to the active roster, James Hawkins of the Detroit News reports.
Thorton has officially satisfied the six-game suspension he was handed in June for a violation of the league's substance-abuse policy. While one would think his return would be welcomed after starting defensive tackle Haloti Ngata (biceps) was placed on injured reserve last week, it's apparent Caldwell may have other plans in mind.