No, it definitely is a gray area. You right-click and see "Ask an AI Chatbot" in the menu? Some people here count that as not being opt-in and invasive because they can see the option, even if it doesn't do anything until you set it up or click the button to remove it. Hell, some people here on Slashdot will bitch and moan if the browser so much as pops up a hint asking if you want to enable some LLM feature. Even ASKING if you want to opt-in is too much for some people.
Some people think that they should not even be aware that a feature exists unless you search for it in the settings menu and enable it. That is "opt-in" for them. And for others, they don't view the browser exposing a feature stub or informing the user about a new feature as "opt-in" if you still need to take action to both enable and use the feature.
It sounds like this "kill-switch" is to placate the first group of people who don't even want to know the feature exists. It will most likely remove all of the dormant feature stubs entirely and the browser won't tell them about the features at all. I think that is perfectly okay.