This may be a blessing in disguise. It's one less choice PC has to make about which defensemen to keep.
Yes, it's always good to have options, and, from a "game theory" standpoint, removing choices like this is technically speaking, neutral at best, and is more typically negative.
But we're not in a mathematical vacuum - we're in the real world. Getting rid of one of the weaker defensemen makes it easier to focus on the remaining defensemen, and the remaining team as a whole. I'd rather that they concentrate on Krug, Hamilton, and Miller.
PC's been telegraphing this decision. He said 9 D is too many on July 1 - granted, Mezaros is gone, but 8 D is still pretty robust for a team that's about to hit the cap, and hit it hard.
I wish Bartkowski the best - on a lot of teams, he should be able to bring something as lower pairing D man. The Bruins are just too damn deep in defense. I'm not sure arbitration's exactly the logical way to go - that seems to signal "I want to leave", which, to the other teams, should in theory signal "I can get him cheaper". But it's all part of the game, and certainly not a cheap shot of any kind.