He only has to bring the car back if there is a specific language in the contract he signed with them. This is easy to check - whatever they printed out and gave him, constitutes the whole contract.
Whatever else they told him then, or are telling him now, is not a part of the contract, and he can ignore that. The US Uniform Commercial Code is very specific about this.
Such “provisionary“ terms are rare for a lease. More likely, they have a “seller remorse” now, what with the stupendous rise in gas prices because of the war in Iran, and correspondingly much higher demand for electric cars.
If they don’t have a valid contract claim, but nevertheless become too relentless and annoying, he may hire an attorney for couple hours, to draft a letter informing them that in case they pursue this any further, he will hit them with a lawsuit demanding compensation for his lost time, inconvenience, and price gap.
Seriously, buying or leasing a car sometimes requires a significant time. For my past lease, I negotiated with no less than 18 dealers - it did take a lot of time and effort.
Then there is inconvenience and expenses related to not having a car for a while, if he is unlawfully compelled to return it right away. It could be for instance rentals cost, Uber expenses and so on.
And, last but not least, if he now has to find a lease of a same or similar car again, and it turns out to be more expensive, this would create a “price gap”, which is a direct financial harm to him.
So, once again, if what they are asking him to do is not in the contract, he doesn’t owe them anything in this regard.