You'd think that would be a good quality to have on your PK.
If the Canucks had a balanced defense he’d probably be out there, but you have to play to your strengths and the bottom 4 who can’t move the puck can at least clear the crease and block shots on the PK. You can say a PK is more important than an ES shift against the 4th line, but that’s only true from the defensive side of things. Hughes’ offensive ability means those shifts are an opportunity to put goals on the board, something he isn’t going to do regularly on the PK. The Canucks bottom 4 D is also so bad currently that they're getting hemmed in by anyone, 4th line or not.
If someone wants to give extra credit for a defensman being elite on the PK that makes sense, and if they also want to take Hughes’ ES numbers with a slight grain of salt because he’s not taxing himself on the PK that’s probably fair too. His relative numbers also need to be put in the context of how bad that bottom 4 is. But Tocchet is using him not just to maximize his strength but to minimize the deficits of the others, and anyone claiming it’s because his defense is poor is just nonsense. There’s a reason he’s being used less than in the past. He’s not an elite PKer but he was pretty average at it in previous seasons.