But you're just assuming it is. It could also be "On uninstall and crash, report back which studies were enabled" to track how many people are uninstalling their browser when the flag stupid_feature="on" is set.
Be mad about the data collected [specifically, what type of data is collected], not about the concept of a/b testing. Set clear boundaries of what is and isn't acceptable. Otherwise you're fighting an ever-uphiller battle. Because if they want to know which sites you visit and the privacy boundary is "a/b testing isn't acceptable", they'll do it via history syncing instead.