It's silly to give such a long list of off-limit D. At the end of the day, you can only play 6 D men at a time. And I think it's a waste of assets to rotate quality D men in the lineup when you need so much help up front.
Who gets traded really depends on how good Pinto can be. I really like him, but I am not an expert and don't know what his final potential can be. If he ends up being a consistent 30g-70pt player, it would be silly told on to Harris, Barron, Engstrom and maybe even Mailloux to an extent, if that was the cost to acquire him.
If Ottawa offers Pinto straight up for anyone of Mailloux, Barron, Harris, Engstrom...I'm not sure I'd say no. I'd only really hesitate with Struble and Arber because they're top potential isn't clear. Guhle and Hutson I would flat out say no.