Same as unmasking
Putting an apparatus on a child that restricts their breathing when they don't understand the reasoning really is akin to child abuse. It's a completely unnatural thing to do. I don't agree that these parents should be jailed, just as it's not appropriate to be jailing people for not wearing masks. He's getting a message across that it's not appropriate to be doing this to children.
When a child can't emotionally handle wearing a mask, they're likely taking a cue from their parent reacting similarly. And nobody is getting "thrown off airlines" because their child took off a mask as they worked to get it back on - they're likely refusing to keep control of their child, or throwing a tantrum right along with them.
I've seen too many histrionic comments saying masks make it "hard to breathe" to take any of them seriously. Plenty of trades wear masks for hours at a time - eg surgeons, construction, auto body. That narrative ignores the benefits of wearing a mask, while blowing the burden out of proportion. Anything can be made to seem prohibitively burdensome when one shirks personal responsibility.