I was gifted this particular appliance, but the solution is really to just not give companies like this your money. Unfortunately it's easier said than done, but looking for things with a local API or based on an open and configurable standard are a good start.
I'll add Haier and related companies to my ever growing blacklist because fuck them for this.
I vehemently support people doing what they want with the things they own so long as it's not "interfacing" with other people or their stuff; don't connect to or "abuse" their cloud systems, they can rightfully be upset about that, but removing their crappy smarts (and data collection) and replacing it with local-only is your own business and companies like this can get lost.
They have no right to be upset about that. They sold you a requirement to connect to that cloud. If they don't want anyone connecting to their cloud, then don't sell cloud connected junk.
I agree with you wholeheartedly that it should be fair game, but ultimately, if reverse engineered users are creating, say, 50% of traffic[0], because they're polling instead of using the proper push mechanism, these sorts of companies can and will get upset.
Frankly, as a backend software engineer myself, if any system I built with the purpose of being constantly accessed by a fleet of devices sold on the open market couldn't handle the relatively tiny numbers MyQ created a fuss[1] over, I'd be embarrassed.
[0] https://chamberlaingroup.com/press/a-message-about-our-decis... [1] https://www.home-assistant.io/blog/2023/11/06/removal-of-myq...