BMI is garbage. Totally inaccurate for anyone with muscle, and doesn’t even account for gender, so usually it places men at being obese when their weight is basically normal.
I didn’t realize it was straight height/weight until I looked up a calculator. I was thinking there was some other factor like neck or waist size in there too. I’ll admit I have a bit of a gut, but I really don’t think I’m overweight at 6’4” 210 lbs. and like you say, someone who was muscled definitely wouldn’t be.