I understand and agree with the moral point you're making. Stereotyping and bigotry is wrong, and I've understood this for decades (as far as I'm concerned it's basic morality, and a core value in my moral compass that's unshakeable). I've known this for so long that I no longer feel the need to explain myself, or tell other people about it, like spreading the gospel. Call me grumpy, but if I'm willing to give a player the benefit of the doubt, I've come to expect it in return.
Since that's who I am, I feel I can be trusted to choose to have orc bandits like Blorg in the game who are acting evil, without having to spend valuable prep time fleshing this out every game. It's impractical when I only have 15 minutes. Also, the players are probably going to kill him off soon, so that prep is going to be wasted anyway. If a player asks me in a game about Blorg's motivations, I'll just make something up on the fly.
What I'm really taking issue with, is how making a big deal out of singling out Orcs as an example of how D&D is morally failing, enables some disruptive players to engage in bad behavior in the name of upholding this moral standard. Because of this, I no longer use Orcs in games, because now there's always "that guy" who's going to assume the worst, just because I have orc bandits. They will jump up on a soapbox to "call this out", interrupt the game, and imply wrongdoing, even if it's not taking place. Strangely, if I have poorly fleshed out human bandits, or inherently evil demons, or a BBEG (like a Sauron) they don't seem to care (?)
In my experience, I've found that accusing someone of being morally bankrupt, or guilt tripping them in front of a group, is guaranteed to anger them, and cause a fight. I don't allow it during game sessions, because it's disruptive. I view it as a form of hogging the spotlight. I have had to cancel games (and ultimately kick a player) over this, because they couldn't just let it go. Bad behavior is still bad behavior, even when done ostensibly for a good cause.
What I want is to agree with the players that we all already know that people are complicated, and that their motivations for evil are there (but unspoken) before the game starts, and then be done with it. Calling out during my game, is not allowed.