I am not licensed in MN so can only answer in general terms. A felon (or someone convicted of any crime of moral turpitude) in WA certainy canot actually serve. I do not know any state where a felon can serve as a personal representative. I assume he is just named in the will and your mother is still alive. Maybe she can persuaded to change it.
Otherwise, you and your siblings will have to challenge his appointment when the wll is probated, on both the felony and active alcoholic bases.
By the way, I spent five enjoyable years in the St. Cloud area, two atending SJU and a few more living in he Avon area. If you need advice, I recommend my friend and former professor Mark McKeon who practices in Cold Spring.
In MN the statutes state that:
524.3-203 (f) No person is qualified to serve as a personal representative who is:
(1) under the age of 18;
(2) a person whom the court finds unsuitable in formal proceedings
Your question focuses on number 2, wether or not the person is unsuitable. As stated previously, should you be able to prove he is unfit as personal representative, then he cannot serve. Otherwise the court will follow the wishes as stated in the Will. Use an attorney to deliver the right message to the court and remove the unwanted P.R. best wishes.