Sure, though you would you only start to look if you had an initial flag to go off of. If account traders are using 2FA to trade accounts without triggering password/email changes (or delaying changing this information past the wake up date or after a long period of time has passed), they might go undetected. My main point of adding the 2FA flag is that it would prompt those who are looking to go and do so/keep an eye on those accounts.
Just like email and password changes, a 2FA change shouldn't be a "prompt" to investigate an account. Accounts should be investigated if it appears they are involved in some kind of wrongdoing, not because they made a change to their profile.
You've only ever tagged 1 account on suspicion that they were an alt account, accused other accounts as being alts in your posts, but never provided evidence to back any of your claims, so you don't have a whole lot experience in this subject. If you did, you'd realize there's better ways to identify scammers / dishonest accounts.