This is a good discussion to be having now, in light of MeToo, Black Lives Matter, Covington Catholic and many other issues in the news.
Whether you call me a fence-sitter or simply someone who believes in nuance, I find the culture of instantaneous mass adjudication of every person or event that comes along a dangerous and unhealthy trend. Humans are complex beings and, a few notable exceptions aside, are rarely 100% bad or 100% good. If I'm being honest with myself, I don't always follow my own moral code on judging people at the drop of a hat, as anyone reading my posts here will attest. (See? Complex!)
Political and social realities aside, I would assert that people should be judged on the totality of their being, not on a single lapse in judgment at a party. If Northam has grown to become a friend in the battle against oppression, that is an important factor in my view of him.
I have made my share of bad decisions, and would probably be trashed if I ran for office, but I like to think my contributions to the world have outweighed my missteps. If you took a poll of everyone I've ever known, asking about my integrity and dedication to equality and justice, I'm confident the results would be mostly positive.
Jeff makes a good point about Robert Byrd. He did far worse things than Northam did, but he changed his ways and he was largely forgiven. Even the king of racism, George Wallace, atoned, albeit imperfectly, for his appalling separatist actions as he got older. I gained a little respect for him as a result. Similarly, rapper Chuck D of the almighty Public Enemy -- a group that supported black nationalism and called white people the enemy -- has long since softened his rigid stance.
Each of us is flawed and prone to errors in both thought and deed. What matters most is what we do next. As Ocar Wilde wrote, and Chrissie Hynde later sang, we are all in the gutter, but some of us are looking at the stars.