You actually can, that is the entire purpose of the 350 being added, to be sold off to new customers because there's enough interest on top of the original plan to allow all 4th-year examples to be open for sale.
Suggest you read my entire sentence as well.
Since you "know of their scheme", you know Ford has been very aggressive in keeping the GT off the used market & away from auction sites. It's part of the reason they chose people to begin with, why the "social media influencers" may receive one so they can "share" the car with the world. Really, it's a great marketing tactic that basically hopes the influencer keeps the car long term. Same with asking how long former GT owners kept their cars and what kind of car collections they own.
So in this case, demand is relevant to Ford because they want the car to remain exclusive.
They took a Ferrari/Porsche-approach with this vehicle for a reason and that entails making sure the value of the car stays in the black for Ford to keep whomever else happy. That involved purposely capping production, picking the owners, and to an extreme on Ford's part, having a sales embargo. With a planned 4-year production window on the biggest hyped car in Ford's history, this would be difficult without the embargo they placed & the threat of law suits (as blacklisting wouldn't work). Without it, as the first of the 1,000 are made, around a dozen could easily find their way to the open market in the first year. Based on the initial reactions I saw, leaving an open window meant the first few cars see $1 million POAs (as a couple actually were overseas), a hefty return on a $500,000 car. However, by the 3rd year run, "fair market" values could then drop if the market became saturated after the flippers made quick bucks. Exotic car owners aren't fond of this, because exotics are the only, relatively, "investment-safe" cars out there, esp. when you're spending $500,000+. Manufacturers don't like it b/c that's extra money being purposely left off their tables when they factor in MSRPs; Ford could've had started the GT at $1m if they knew people were willing to pay that in the market, but that price point would reflect more negatively in less initial buyers, their company image not being known for that, etc.
The embargo however, kept the car harder to buy, which boosted the value, which keeps the ownership base happy. If you took notice, this additional 350 car run is being added just as the original sales embargo has come to an end & production is set to end in October. First year cars are starting to hit the auction/used markets without backlash from Ford, and their initial values are still around $1m+. That's great for the owners looking to sell now since Ford has already secured their own financial interests & the 350 supply (alongside the Mk. II) is extra money. On top of that, with production closing and a reported 6-to-1 demand, values should stay pretty high for years to come as long as the market remains limited over time.
Ford took a risk being "reluctant to sell" and it's appearing to pay off for those in that circle.