Sorry, but your post is inaccurate.
Tavares was a PPG player last year. Sequin, although over a year younger, has not come close to that since the 2018-19 season.
As you stated: "If you're paying a player the highest price point in the league you should be expecting them to still be a top player in their early 30s." As a PPG player, Tavares is still performing at a high level, just not as high as he performed as a younger player.
I fully expect Matthews to perform at a high level when he gets to his 30's, but not as high as I expect him to perform for the next five years which should be his prime.
The Matthews contract is very good for both the team and the player. Some are worried that Matthews will be overpaid if he signs an 8-year contract that takes effect as he turns 31. Agreed. But don't assume that the Leafs will be the team overpaying at that time.
And by the way, you did not answer my question about the perfect length of contract for a player who is 27 or 28.