Can they do that?

No can’t trade him for a year if they match.

But can they trade the matching rights which is what is happening here

No. They can’t. They have to either match or he’s on Carolina

This doesn't seem like enough. This KK contract doesn't do Montreal any favors for KK's trade value

hey do you have link to where it talks about that.
i have never seen it done or heard of it because offer sheets are so rare so be interesting to see the rules on it.
the only thing i see says no trades after matching
https://www.capfriendly.com/offer-sheet-faq

cant trade a player until 1 year the OS.
https://www.nhl.com/news/nhl-contract-offer-sheet-questions-answers/c-308047180

"If matched, the player remains with his team under the terms of the offer sheet he signed and he would not be eligible to be traded for one year."

so if Montreal matches KK....they will have to QO first to his 6.1m, try to extend him, or he will accept his QO before he is eligible to be traded. He has all the control to how valuable he is as a traded piece 1 year later bc of the timing of the OS. It was smart business by him and his agent

I don't have a link, but I can assure you that you cannot trade the player within the 7 day matching window either. He technically doesn't belong to you until you match, and he technically doesn't belong to Carolina until the 7 days are up.

Montréal and Carolina are the only 2 teams that Jesperi Kotkaniemi can play for next season.

If not match and trade

Even if they could do this trade with KK (which it doesn’t seem like they can), why would BUF accept? That’s a very underwhelming return.

Not exactly true, Montreal and Carolina can still work out a trade and the OS can be rescinded. However they are the only 2 teams that can do this.

If this is legal, MTL takes this offer and runs.

I'd need a source for that because I don't recall it and it doesn't make sense.
Rescinding an offer sheet can't be right. The player already has that contract. There's just a "blank" where the team name goes.

It was discussed by several pundits when we OS Aho, I will look for a source though

thats false, they cant negotiate a trade now. That contract has been submitted to the NHL registry. the Offersheet just doesnt go away. Kotkaniemi can not be traded in the 7 day window. Its in the CBA

so if kk rights are traded to buffalo and buffalo (not mtl) matches then that's not an issue. buffalo would then just not be able to trade him for a year.

did you have a link for that rule or where it talks about that, it has not been posted on here yet.
this may be the loophole that not in rules if nobody can find specific source for it.

i just tossed up a frame work of what mtl could do ideally i want more but wasn't the point of post.

Technically Carolina owns his rights unless Montreal matches. He signed a contract with them. Montreal can match and take over that contract, but then they can't trade him for a year. So KK, rights or otherwise, can't be traded to Buffalo.

i technically would need to see the rules to validate that. he is mtl property until the 7th day is up according to what i have seen

Exhibit 6, 10.3 (a)
Once an Offer Sheet for a Restricted Free
Agent has been received by the Prior Club, the Prior Club may not Trade or otherwise Assign its
Right of First Refusal for such Restricted Free Agent.

I don't have a link but I remember the context of the trade proposal talk. It was actually talk of arranging a trade so that the original team does not match and let's the player go. So in this case Carolina would agree to a deal where Montreal gets the comp package + a prospect and Montreal let's KK walk. So technically it's not a trade involving KK but in a sense it is.