Looking at https://searchfox.org/firefox-main/source/browser/components... it is a bit weird, that there isn't a general check for browser.ml.enabled true/false.

Yeah, there should really just be one global setting.

Also note that it's browser.ml.enable (no "d") vs. browser.ml.chat.enabled, to make matters even more infuriating.

I think the option to disable the context menu item is right in said context menu. Best place to put the option honestly, I wish all AI features had a disable button right next to them.