Earlier quoted context omitted.
Why is the burden always on the individual to not "burn the bridge"? I'd say that this startup has burnt this bridge pretty well. It would have been perfectly reasonable for him to tell us who they were and for us to avoid them like the plague.
having been a bridge burner i can say that most employers are not competent enough to discover that you burned a bridge if they care... and if you volunteer the information its a great way to filter bad employers too.
Just as most companies are too incompetent or uninterested to search out your dirty laundry, most companies are too incompetent or uninterested to sort it. If they see it, they'll just acknowledge its existence, and probably think twice about you because of it. They won't dig deeper, or spend any effort sussing out who was right and who was wrong. They'll just note it as a red flag.
This is why people advise against "bridge burning," even when you have no reason to believe you'll ever cross that bridge again. It's all about perceptions. "Optics," as they say in corporate parlance. Being seen as a malcontent is never good for your employment prospects, even when you're completely justified.