I think you are right and have framed the concept or principle correctly.
But let's take a devil's advocate approach to this and look at from the perspective of the potential suitor GMs.
In your example with three teams, would those GMs just bid a little lower in the initial phase thinking that their goal is to not overpay and to bid just enough to secure discussions with the Debrincat camp? And, if Dorion knows it's better to get a bidding war going, would he not be inclined to allow all those three teams to speak with the Debrincat camp? I mean Dorion could potentially eliminate a low ball bidder using the technique being described. But, I got to think the other GMs are going to be smart enough to think about a good strategy on how to play this situation, and that Dorion cannot be too restrictive because there's risk not having enough potential bidders for Debrincat's services. But in the end, if the GMs who are interested are smart & play their cards correctly, you kind of end up in the same place you would ultimately without this process.
Anyhow, I think I'm just interested in the process and bouncing ideas around (thinking out loud) because of that interest. I haven't really formulated any set in stone type ideas on this, but find it kind of fascinating.
For sure, I find the discussions about how a GM goes about their job super interesting too, especially in these types of situations where there's a significant roster player potentially getting moved and the GM has to carefully navigate in negotiations to get the most value for his asset. I'm not going to pretend to know the inner workings of the front office for these types of negotiations because I really don't, but my take on how Dorion would proceed is this:
1) Dorion would set an internal deadline to field offers from interested teams. I would assume that he would want a pick or picks in this year's draft as part of the return, so let's say he would set a deadline for 3 days prior to the draft to receive offers and negotiate trades with other teams.
2) During the period before the internal deadline, Dorion is using all usual negotiating tactics as he would in any other trade. Pitting offers against each other to try to create a bidding war, making pitches to get teams to increase their offers, etc. That's part of his job as GM and his skill in handling these talks will determine the strength of offers he ends up with.
3) Once we get to the internal deadline that was set, Dorion reviews his options and chooses all of the tabled offers that he would be willing to accept if they were final offers for a signed DeBrincat. Let's say that there were 5 serious offers submitted and Dorion has 3 of them that he really likes and would accept. Dorion then goes to those 3 teams and let's them know that they have a deal in place, they draw up the paperwork so that it's ready to go but nothing official sent to the league yet.
4) The 3 teams with an accepted trade offer (let's say Detroit, Dallas, Carolina to keep with my previous example) now get to move on to the next stage of the process. With an accepted trade offer now in place, Dorion all at once grants permission to Detroit, Dallas and Carolina to speak with Cat and his agent. These three teams now enter into a UFA style negotiation with Cat's camp on a new contract.
5) The 3 teams fight amongst themselves over the next couple of days to iron out a new contract with DeBrincat. Ottawa doesn't really care about this part other than it getting done in a timely manner so that the accepted trade can get processed before the draft. As in the example of my earlier post, if Cat prices himself out for Carolina and Carolina is no longer interested, Dorion was still able to use Carolina's trade offer in the earlier stages of the process to leverage Detroit and Dallas into submitting offers that he would accept in a trade.
Using the accepted trade offer as the condition to be allowed to speak with Cat's representatives ensures that Ottawa would receive an interested team's best offer. If an interested GM bid a bit too low to try and secure themselves a better deal, they get eliminated from the process and never make it to the stage of trying to talk with DeBrincat about a new contract.
I follow the NFL quite a bit too and I remember from the Deshaun Watson trade that Houston had accepted trade offers with 4 teams that Watson was willing to waive his NTC for. IIRC the accepted trade were with the Browns, Panthers, Saints and Falcons. Then for about a week, the 4 teams courted Watson, brought him in for visits to their team facilities, negotiated with him, etc just like they would for other big-name free agents. Watson ended up taking the contract that the Browns offered him which led to Houston making the Browns trade official over the other 3.