Is it wrong to judge how people behaved in the past based on today's morals?

You do realize that subjectivity is an abstract and cannot be explained in concrete terms. It something that doesn't exist.
Laws are an abstract and someone\something else's notion and perspective of what things are. I may or may not choose to buy into it or agree with it, but the bottom line is, I don't need others to tell me how I should act and think and if my behavior is not contravening any asinine written law, then it is irrelevant to my state of being. If I break a written law, it is also irrelevant, because I didn't pay heed to it. Consequences can ensue, but that is just part of the systematic game and depending on the severity of any action, most of it is bullshit. It is ultimately meaningless, manipulating and insidious, for an institution to tell me how dare I not follow it's golden rules and pay heed to it's self-aggrandizing and overbearing self-importance. This is kind of like how you express yourself though. It's no wonder you are disempowered. You give it away to others, that you think know better. How pitiful!