It's been almost a year and it still works fine. I even set it up as a dev account to sideload apps and make calls to the wit.ai api in a few projects.
It depends on how much you share that account, is my point. While internet randos using it would obfuscate any one persons activity, I am not sure how it would work in practice. Maybe you are already sharing it with a dozen other people? I dunno. Security bots tend to clamp that kind of thing unless Meta really gives zero fucks.
Dummy accounts work for something like Lemmy but when you're playing with big tech corpos in 2024, it doesn't matter how dummy you make it, they will know it's you.