It is necessary for some miners to choose to use the post-fork software in order for it to work, but miners take on the task of mining due to financial incentiv

It is necessary for some miners to choose to use the post-fork software in order for it to work, but miners take on the task of mining due to financial incentives, and the users ultimately control those incentives. Miners only have a choice in the sense that they could collectively choose to abandon their profits as a matter of principle.