I agree. He should have been tried, and convicted, and put in prison. It was a miscarriage of justice that he was not. But even if all that had happened, it shouldn’t make someone ineligible for office, otherwise it could be abused by a corrupt government. Ideally it would make someone unqualified in the eyes of the electorate, but… well I wouldn’t count on it these days, unfortunately.

And despite that Trump was allowed to run for president!

I wouldn’t want criminal charges from preventing someone from running for office. Otherwise someone like Trump, once in office, could just get his justice department to file charges against any candidate that he didn’t like. It is a failure on the part of the voters to have elected him despite the criminal charges (although not the only failure, certainly).