IANAL or board member or anything of the sort, and I would refrain from arguing with his personal political opinions just because there's no winner in arguing p

IANAL or board member or anything of the sort, and I would refrain from arguing with his personal political opinions just because there's no winner in arguing politics with him, but it might be prudent to have a little discussion about avoiding politically charged topics when in a position to publicly represent the company. Tell your board members to do what other famous people do when they want to vent and shitpost on Twitter: create an anonymous burner account and have fun going buck wild with no trace back to you.