The second bolded is exactly why you trade him.
By the time we might actually want/need the cap space, Skinner's buyout becomes entirely reasonable.
If we wait until summer 24 (Mitts, Dahlin and Jokiharju need 3rd contracts, Krebs and Quinn need 2nd contracts), we would save money for 3 years and then be on the hook for 3 more to the tune of 2.44M. Very reasonable.
If we can hold off until the summer of 25, then it's a complete no-brainer.
Buffalo isn't likely to need the cap space in 22/23......or 23/24 for that matter. Hell, 22/23 we'll likely hold onto his salary to hit the floor again.