The reality is it does look a bit thuggish, and by extension when you see a 3 year old acting in a normal 3 year old way, maybe being a bit boisterous, the shaved head only adds to the perception that the child is a thug-in-waiting.
This is from someone who had a number 2 all over for the first 13 years of their life, and has had one periodically since, so I'm not coming at it from a place of snobbery, I've lived it.
You also can't help but notice patterns among the children at school who are aggressive, disruptive etc, and the style choices they or their parents seem to go for. When I was at school it tended to be lads with shaved heads and slits in their eyebrows, I'm not sure if that's even still a thing? Bare in mind this was in lower school. As an adult it all seems so ridiculous.
Our heads were shaved because our Dads head was shaved. His head was shaved as he couldn't be arsed with washing or drying hair when he had to get up for work at 1am.
My hair is now 3/4 of the water down my back, and has been for the better part of 15 years, with the odd foray back to shaved. That has its own negative connotations.
The thing is, you can't stop people judging, or sniping behind your back, whether it's right or wrong. Just look at this forum, doesn't matter what it is, there are people lining up to sneer at it. I'm not exempt from that, there are plenty of things or people I view with disdain. All you can do is accept what some people will perceive, and own your choices in life.