I mean, they can decide to only provide maintenance and software upgrades to the original buyer in the first year. That's their business decision and the market will decide whether this makes their product less alluring or not.
But if I buy something, it becomes my property and I can do whatever the hell I want to do with it. Or did I miss a memo?
Probably not.
The following is a simplification and approximation.
A contract is a legally enforceable promise. What turns a promise into a contract is "consideration".
I don't want to delve too deeply into this because something like 80% of the Contracts class in law school is trying to figure out what the heck "consideration" actually is but roughly it is a promise, action, or restraint from action bargained for by a promisor in exchange for the promise.
In this case, Tesla (the promisor) is promising to transfer ownership of a Cybertruck to the buyer and in exchange for that promise wants the buyer to pay money and restrain from reselling the Cybertruck within a year.
What seems to get people hung up is that if you own something you can generally legally sell that thing. But that's what makes agreeing not to sell work as consideration. Consideration has to have some value.
If the purported consideration is doing an action that you were already legally obligated to do or refraining from an action that you would not have been legally allowed to take it does not have sufficient value to work as consideration.
Agreeing to refrain from an action you can otherwise legally take is fine as consideration.
The point is that the contract is bound to the person who accepted it, not to a property itself (there are exceptions for specific types of contracts on realty).
You agree to a terms and service and if you violate them you will be punished by having your car blacklisted and blocked from superchargers, updates, service at Tesla dealerships, warranty void, etc. Accept it.