I don't like this at all for either team. Particularly doesn't make sense for Seattle...but i don't really like the wager from the Habs end either.
Guhle has legitimate top-pair potential, in a guy who can seriously skate and plays a physical brand of hockey. Those guys are invaluable...and he's really not that far from reaching that point. I also don't really see the Habs having the high-end replacement for what Guhle is intended to be for their future blueline. The emergence of Hutson as an offensive D doesn't really eliminate the need for a guy like Guhle down the road as a counterpunch to that. And outside of Hutson and Guhle, Habs defensive depth of prospects/young players is more "quantity" that absolute top-end "quality". Matheson is fine now, but he's not the real long-term answer for a contender down the road.
But all that is rendered irrelevant, because the assessment of Seattle having an expendable Top-6 Center and arguably their best bet at becoming an actual 1C of any sort, is just completely 180 degrees off base from reality. It's far from any kind of guarantee that Catton is going to be anything special at the NHL level at all, and heck...it's not even a slam dunk that he'll be able to hold up as an NHL center (very plausible that he ends up on the wing). In any case...Seattle don't really need to upgrade their defence corps. It's not elite, but they seem pretty content with the sum of it's parts being at least "good enough". What they desperately lack...is high-end offensive talent, and particularly...anybody who looks like they have bonafide #1C potential. Which makes Beniers...about the least tradeable asset on their roster...even if his contract is a risky gamble on growth and development in his scoring rate back on track to previous rates.
Just doesn't really work for either team. Particularly in where they want to go longer-term with their roster construction.
Something around Matheson for Stepheson would be more in line with what makes sense in terms of swapping around veteran "stopgaps"...except for the fact that the Kraken don't need Matheson whatsoever, and Stephenson is still plenty useful to them even if it's just a "center by committee" approach going with a trio of 2Cs.