It's really a bad position to be in for MB.
I understand the sentiment of letting him walk - a 1st and a 3rd for what we've seen of him to date would be great value. However, MB let Danault walk probably thibking of Kotkaniemi as a staple in the top 9. If he lets Kotka walk, he loses 2 top 9 centers in one year, and your new 2C is either Jake Evans or... Ryan Poehling? It's just a really bad look for the "GM of the year finalist". There's also a not insignificant chance that Kotka steps up to be a 40-50pts C next season, and then letting him walk sucks.
But then, signing him means that he NEEDS to produce at that rate, otherwise you lose him for nothing next year (are we really gonna qualify him at 6M if he's yet again a 30 pts player?). And if he does step up, you pay RFA years at a premium... which is just plain dumb.
So, MB's probably gonna have to match to keep his job, but he's losing either way. This offer sheet is lower in value but is much more damageable to MB/the Habs than the Aho offer sheet which was laughable at best.
Oh, the Canes could miss the playoffs and win the lottery sure... but would you really bet on that as the hockey workd laughs at your incompetence as a gm?