You still have to factor that in, he has to come off IR eventually and you have to plan for that as well.. which is also part of why Waddell wanted to move on from him, to allow for more flexibility.
Not to mention not every injury is IR worthy.
I think the main reason Waddell wanted to move on from him is that Laine wanted out. The Odds of Laine being a productive player for the habs are probably higher than Waddell actually using that extra financial flexibility. The only expiring contracts he has for next year that may command a significant increase is Provorov (assuming he extends) and maybe Voronkov.
At the end of the day, obviously the Habs prefer if this works out but the downside is minimal. The Habs did not need that 8.7M of Cap space this year or next year. 2026-27 is when the next group of expiring contracts will need money. Hard to spend the cap space this yr next yr on a significant UFA add as no one of that caliber will take a 2 yr contract. They kicked tires on guys like Marchessault but term did not fit.
For next year Habs have
Armia, Dvorak, Evans, RHP, and Savard contracts expiring. (maybe Savard and or Evans gets extended)
For 2026-27 habs have
Laine and Matheson as UFAs
Dach, Roy, Hutson, Mailloux, Barron, Xhekaj as UFAs
That's the year the need the money. Following season there will be others Newhook, Reinbacher, beck and maybe Demidov but more $$ frees up from Anderson and Gallagher at that point.
There is a risk that Laine does not perform but it does not affect their ability to extend their kids and ultimately he did not cost them anything other than Molsons money. There is no real opportunity cost as they could not use those dollars in UFA market anyway without a longer term. Could they trade for someone else with 2 yrs left, yes in theory, but not at the minimal price they paid for Laine.