Don't let them sell your Berkshire Hathaway shares
They're going to sell your Berkshire shares whether you consent to it or not. If you are okay with that, fine. But you put them in there for a reason. At one time, you wanted them. This company does not have your best interests in mind and there's nothing wrong with having some company stock in your retirement portfolio. These are your shares you earned working for this openly hostile company that has screwed you every chance they had. Whether or not you believe in the company, this is a stock you probably want in your long term portfolio.
Transfer your shares to an IRA you control. They are your shares. Is management using this as an opportunity for a small buyback they can get away with at a discount? Who knows! A massive market buyback would tip off investors and the price of the stock would rise. Buying the shares from you doesn't cause that in the same way. Their reasoning for this intrusion into your account is not believable. Shielding you from the exposure to a single stock is not a sufficient explanation when you yourself chose to put that stock in there to begin. Generally speaking, one stock doesn't belong in a 401(k). Berkshire is different. Berkshire is massive, as you know.
GEICO employees have had the option of Berkshire stock for decades. This change is ridiculous. Whether you want the stock or not, this is an intrusion into your accounts. If you wanted to sell the stock, it should start and end with you. Not GEICO.