So if I buy one, I'm not allowed to sell it after I'm done with it? That's irregular, to say the least.
But this looks more like the reseller is trying to wreak havoc with lawful competition sans an agreement with Amazon. They may not look kindly on it if they see what's happening. Competition where it's not being intentionally stifled is the business model.
If you, dear reader, had a sole distributor agreement with an OEM would you do what you could to protect your reputation and the brand?
Which law prohibits the distributor from selling thermometers that they own?
How come an agreement between ETI and Thermoworks have any legal power over anybody else?
You can always buy the product at retail, from another country, or directly from the manufacturer (if they will sell to you) and sell the product at retail.