Shareholder change through retirement

Rather strange question - I hope someone is able to help me.

I have been contacted by a friend whose Managing Director (and shareholder within the company) has effectively had to leave the business via retiring as a result of mental incapacity. My friend reports directly to the MD as well as the other shareholders - it is a small private bar. He has been told today that a friend of the MD has taken over both the shares and role of Managing Director, presumably through power of attorney (?) and that the other majority shareholders were unable to do anything about this.

My question is whilst I appreciate taking over the shares, would someone acting on behalf of someone else normally take responsibility for their job as well? The original MD had written to the other shareholders retiring prior to the incapacity so I would have assumed the "employee" element of the person's engagement with the business would now be something for the shareholders to decide on and not automatically transferred to the person acquiring the shares.

My friend is concerned as the person in question has persistently undermined him in his role as a customer in the bar and he is worried that as he is now line managed by that person that there may be complications arising from this.

Many thanks in anticipation