I still don't think anyone is going to pay him to be their LT. You just don't gamble on that.
Vollmer is an excellent RT, but his mobility has declined in the past year or two. Also, those back issues are not something to dismiss easily. Truth is, Vollmer has only played 5 games at LT, the last time being a few years ago as an injury replacement. Paying him big bucks to play LT seems like a reach. If you want to argue that he provides a team insurance having the ability fill-in at LT, then OK. But making him your main man protecting the backside of your franchise QB doesn't make good sense. JMO.