> LinkedIn offers no way for $company to disavow users who claim to work for $company - they will appear on the official company page as long as it's in their profile.

It isn't at all a neat solution, but you could maintain a list of users on LinkedIn that are authorised to speak for your company, linked prominently on your profile with a warning that anyone else claiming to work for the company is likely a scammer but LinkedIn offers no way for you to stop them claiming to be part of your company.

If that became a common pattern it could highlight how much of a scammer paradise LI can be and maybe they'd be more likely to do something about that particular vector.