I wouldn't mind keeping Steph for the minimum, but it's possible we might be able to get something better for the same, and it's also possible he might not accept the minimum for a whole year and prefer to retire (or find something elsewhere, who knows).
I think that's mostly what Doc was saying.
I really think Steph did a pretty good job at doing what we needed him for, which was to provide decent minutes backing up Rondo doing what a decent point guard does...handling the ball, running the offense, passing etc. Stephon generally speaking did those things well. We didn't acquire him to have a great scorer off the bench (we have Eddie for that). We acquired him because Eddie is not a good pure point guard. To Steph's credit though, he did come up big in one particular game scoring 12 points in one quarter which sparked a comeback in a playoff game. You can't say Steph wasn't valuable.
That said, I think we could definitely potentially find some one better on the FA market for around the minimum. I'm not sure exactly what the list of vet. PG's will be, but I imagine there will be at least one option that looks potentially more appealing than Marbury - even if Marbury will show improvement playing with the team for more time and getting into better basketball shape.
In any case, we do need to be wary about having a decent backup PG and not just get one midway through the season because otherwise if Rondo is ever injured we'd have nobody except Gabe Pruitt to fall back on, and that's a scary thought indeed.