If an Instance Owner holds a vote and 98% of people say they want to Fedi with Threads, and the owner Defederates anyway, they can do that because they own it. It will make those 98% unhappy, but that’s the price of being on that owners Instance. The owner has execute authority.
So the alternatives are - in order of difficulty and effort/cost 1.Make a Threads account 2.join a Fedi that is still federated with them 3.Make your own.
If the 98% were actually that unhappy and did literally anything other than staying and creating content on that Instance, then it reduces traffic to that Instance. And the owner is left with a ton of sunken cost in hardware for not listening to a 98% vote. That’s how capitalism is supposed to work, right?