To be blunt, I've never had folks tell me to be careful about having a white/het/cis/abled male as the lead. Or the sidekick. Or the villain. The caution about unsaleability always comes with those who are considered minority or special interest groups. Then it's suddenly "Do only what the story requires or it will be message fiction." (Sat on a panel with a dude who literally yelled at an audience member about this and completely shut down the conversation. We ended almost 20 minutes early because no one else wanted to talk after that.)

I am, quite frankly, past the point of assuming best intentions when folks tell me that I need to be careful about having a queer or PoC or female character as the lead. If that's something that is a red flag to a reader, they aren't my audience. (And, sometimes that instinct is just that - an instinct. We read what we are familiar with. But straight/white/cis/abled male saves the day is a damn message.)