"Forbidding or preventing employees from engaging or participating in politics" sounds to me like a company can't prevent you from voting, or attending a political rally in your non-work time. It doesn't sound to me like a company can't make decisions based on your 'political' views, including treating you more or less favourably relative to other employees or candidates.

I put political in quotes back there simply because it's a word that can be bent in all sorts of directions to mean anything from Politics to simply having an opinion on something. Remember, the opinion might be highly offensive and make working with others, on a team, more difficult.