Because at his cap hit, he's an expensive option for the bottom pairing and any term he signs for blocks Bouchard from NHL employment. I'm not sure the coaching staff trusts him in a top-4 role (I wouldn't long-term).

Only reason to move him is to clear some cap space and clear room for Bouch

If you are trying to clear cap wouldnt you want to trade the guy making 4 million who is worse than Benning? (adam larsson)

For Bouchard to come, he can’t play on the second pair of Bouchard isn’t ready for second.

Go easy on larsson the dude plays far more significantly tougher minutes than benning. I do love benning is a fantastic 3rd pairing I suspect he might be ok on 2nd pair but larsson and bear ahead of him and bouch coming in. It’s a victim of circumstance. I know and agree he’s insanely dependable. I am a huge benning fan and really hope he lands somewhere he gets a chance to continue growing his game.

Because he is an expensive option as a 6-7 defenceman.
When he gets used as a #3-4 defenceman he can’t handle it and makes mistakes. He’s decent with 12 minutes a game and has a good shot. But his plus minus is based on power play time and against 4th line players.