I guess they took the lesser of two evils.
If they tag Steinbach, he'll get the average of the top 5 OL's salaries. That's pretty steep, but they may feel he's worth it and don't want him to hit the open market, where they'd get nothing for him if he leaves (as opposed to getting draft compensation if he's tagged).
Plus, Jones is a LT rated by many to be in the top 5 in the NFL in ability, so there's no way a team should let him go. In my opinion, I think that, all things considered, he'd be my 2nd choice of any LT in the league w/ Walter Jones being first. Pace and Ogden are both still very good, as is Willie Roaf, but all of them are up there in years and if I were managing an NFL team, I'd put the big bucks on a great young guy like Levi before I'd go after one of them.