So what if your horse throws her head, braces, pins her ears, just acts pissed off in general when you ride her bitless? Would you decide that she did not like the bitless? Or would you keep working in the bitless?
My mouth isn't nearly as bit as my horse's nor is it shaped correctly, but when I was child my siblings and cousins would often put "bits" in our mouths and ride each other. It wasn't uncomfortable in the slightest, unless the "rider" was yanking on it.
Obviously that doesn't work because it wasn't in a horse mouth. I believe bits are uncomfortable and don't agree with them. That won't change the mature thing is to agree to disagree.