I doubt this policy is based on any sort of broad principle. Youtube just doesn't want its platform to play any part in the currently ongoing coup attempt.
If there is widespread election fraud (which has not been proven and includes an undefined term used as a negative persuasion tool "widespread" anyway) then that is the coup attempt you refer to and their platform is host to uncountable instances of people claiming a certain person has been elected and now there will be no counter information for people to consider the alternatives.
Yes, that's true. Again, I don't think this is about any higher principle; many people just aren't willing to maintain editorial neutrality with respect to a coup, and I don't think it's reasonable to expect them to.