Can probably throw in another couple of reasons, not specifically Kakko related because I'd rather keep him.
Gourde scores at even strength.
Gourde also immediately improves pp2 as well.
I think you could get Gourde for a mix of picks and Chytil which means you are only increasing the salary by gourde - chytil so 5.1-2.3=2.8. Now if u also got rid of Nemeth and his 2.5m along the way....
Retention just is so Gourdes addition keeps us future proof. I'm notnsure Seattle even asks for Kakko so I'd rather trade picks and a prospect. If that offer sheet comes then you regsrld the picks you just lost on the trade anyway and then have even more cap space.