You are quite correct but here is my theory(and plenty of other peoples theory too)...
Okay this might get a little long.
Jigsaw doesn't only kidnapp criminals he kidnapps people who do not appreciate there lives and take it for granted.In saw ones case gordon was cheating on his wife with his secratary's/hookers and neglected his daughterso jigsaw acted on that as he doesn't appreciate what he has.Adam has been sitting in the shadows watching people's lives meaning that he invades peoples privacy and takes pictures of there every move.
The only way adam could've got out if he cutt off his own foot which is why he was left there to die,he didn't have the survival tool to stay alive but gordon took had what it takes to survive and felt guilt.Dr.gordon could very well be alive and he was a doctor he knew that he could survive with one foot(he didn't die from bloodloss there wasn't that much blood anyway)but when gordon left jigsaw got up and closed the door on adam meaning that he would've saw gordon crawling....A.) Jigsaw helped him up and stiched him or B.) Jigsaw walked over him and proceeded or C.)Killed gordon .... You be the judge
My 1st theory is that Dr.gordon is originally apart of the game,look at when amanda brings adam and gordon into the bathroom,Gordon looks like he comfortably asleep and looks like he put himself into that position , and in one scene gordon introduces John to the interns and you can clearly see on johns bed a book open with a gian green X in it (why would he have that open with his victim right there?) and if you remember gordon's tape jigsaw says " REMEMBER X marks the spot " why would he say remember? jigsaw doesn't say words for no reason ... Also remember adam has the tape recorder so when the tape finishes jigsaw says "follow your heart" very quietly .but yet gordon can hear something from the other side of the room when adam heard nothing but again gordon is soo eager to get that tape recorder from adam,the "follow your heart" phrase almost seems like it has 2 meanings
1)the heart on the toilet
2)It's almost like jigsaw is telling gordon to cut off his foot to get out.
REMEMBER THESE ARE ALLL SPECULATION THIS COULD VERY WELL BE ALL WRONG.
http://www.youtube.com/watch?v=Ol6y9LnKr38