You know, in the Ralph/Littman days, this would've been a routine cutdown day move - release a few higher-priced depth players to salvage the bottom line on the eve of the season, after most of the ticket purchases had been committed.
Now, it's really hard to say. But he's a smart, dependable edge-setter who is scheme-versatile. Not to mention, they have no linebackers for Rex's 3-4/hybrid. It seems asinine but perhaps there is more to the story.