My understand is that was a salary cap related move. I think the dude still can play.
Well, the Rams had pleeenty of cap room AND Laurinaitis was willing to take a pay cut to stay. That he was cut nonetheless is NOT A GOOD SIGN, PEOPLE!!! Neither is him having back-to-back injury-ridden seasons, nor ranking 2nd worst ILB on PFF - 5 spots lower than Nate Palmer.
Rams fans, who have watched him the closest, were like: "Mild surprise...but makes sense, since he was getting slow, not producing and too expensive. Let's get younger and faster!"
So what exactly makes you think the dude still can play? I guess, IF he managed a wholly healthy season from that extremely beat up body, then yes, it's possible he could play - at the same run-D -oriented spot that young and cheap Ryan and Barrington play. No way he'd be the athletic coverage/sideline-to-sideline roamer we currently lack.
In one way you may be right: The LA Rams may be clearing cap room to do some big splashes in UFA to drum up interest in the team. Dunno if that quite qualifies as a cap move, since the team also has to, you know, win to get long term interest. They would not let their best players go, especially ones willing to take a pay cut.