I think it is much worse than the OP article points out.
All things considered it started before Trump's time in office, where we see repeated calls for people to "be held accountable" for prior actions no matter how arguably mild they may have been with no real means to remedy things. Ralph Northam's picture goes beyond some mild event but at the same time we have no real evidence that he is either racist or insensitive to racial matters today.
We cannot discount that things have gotten worse in recent years with all the political rhetoric, and I would tend to look at what really happened across the nation over the past 10 or so years watching DC rip itself apart in a haze of division oriented politics capped off with how some seemed to react to having Obama as President.
But there have been other social understandings that have shifted in just the past decade. Everything from business elites to supposed Hollywood elites treating women horribly for long enough, who knows how many kids harmed by the church sex abuse scandals, numerous racial injustices, and all the other things going on that forced to the surface an ugly conversation on how people treat one another. Today and during their upbringing.
It is an awkward time but actions taken, or even inaction, from 20 or 30 or more years ago have devastating consequences in the court of public opinion, often fueled by those who have a greater interest in finding injustices than actually doing something about them.
The calls for people to step down, or "go away," does nothing for trying to advance away from the ideologies that made those events plausible in the first place.
Is Al Franken a terrible person? Probably not, but what he did do was monumentally stupid. At this point I tend to think Franken was a political pawn in the efforts to do something about Trump over anything really related to trying to improve how men treat women. Is Ralph Northam an insensitive racist? Probably not, but being in the picture was stupid and even if removed from office that removal will do nothing for why those racial sensitivities are there in the first place. (BTW, for the record I am already suspect of Ralph Northam apologizing, then saying it was not him, and now... I have no idea what the next story is.)
Without education and redemption there is zero opportunity for advancement, and the likely outcome is leaving a bracket of the population behind the times with the express purpose of having a bad guy to point to calling them as such. The real trick is going to be determining the sincerity of the next person that is caught having done something 30 or more years ago they would not do today anyway but end up in the headlines anyway. I am not blindly saying let people off the hook for their actions, but I am saying there has to be something reasonable here.
Are there other examples we can evaluate in a sea of those already told to never come back?