Its fruitful to reflect on such past behavior both professional and personal. I have my share of regrets as well. None of us are without fault, just some of us have our mistakes more amplified than others. It important to learn from such things.
In interest of personal edification (since you seem to be open to feedback) the one criticism I have about the Noordhuis incident is that in my opinion if you felt as strongly as you did about publicly chastising Noordhuis it should have been done from your personal blog and not from the Joyent blog. I feel this was slight abuse of power and influence of the Joyent brand, specifically because you mention the intent on terminating his employment if it was within your power. I don't think that belongs there as permanent public record. That said, I think your desire was to make it clear to the community that gender biases were not going to be tolerated and to me that intent (for the most part) came through.
I do think its plausible that Noordhuis wasn't quite represented properly and that he had strong opinions about process and how commits are merged but those strong opinions were interpreted as an intent to have gender bias. But I don't have enough information to know for sure, that's just how it looks to me.
In the end regret is an entirely personal thing and we all get to decide what kind of person we are going to be. I would also like to suggest that regret isn't black and white there are always ways we can conduct or communicate more effectively and perhaps this could be a take away for you. Could there have been a way to achieve your goals equally/more effectively with less of a direct expense to Ben??
As someone who has worked directly under (and along side) you I have a deep respect for the way you conduct yourself professionally. I see you as someone with integrity, which is probably why you feel comfortable bringing up incidences you have been criticized for (this something far too rare). I offer my perspective as a friend so take it for what its worth to you.