Jackson scored scored an injury-time winner in a 1-0 victory against Bristol Rovers after coming off the bench.
"He understands sometimes he'll have to sit and watch for a short time."
The Canada international was named among the substitutes for a second successive game even though his manager changed both starting strikers after a 0-0 draw at Yeovil.
New signing Chris Dickson and Rene Howe started against Rovers.
But Stimson insisted that did not mean Jackson had fallen down the pecking order at Priestfield.
"Chris scored a few goals for the club in his last spell, but Simeon's done better than that and he knows how highly I rate him."