This rubs me the wrong way given that very many people need orthodontia for medical reasons, because their bite would otherwise be so wonky it leads to pain, or to extreme wear on the teeth that can lead to losing them. When orthodontists correct a medical bite issue like this, they straighten out the teeth, too - maybe more than is necessary, sure, but it's generally better to overshoot and be sure the pain or cause of damage is fixed rather than not doing enough.
Nobody should be ashamed of crooked teeth: this is true. But equally, nobody who has hollywood straight teeth because they needed a medical issue fixed should be shamed and told they look "creepy" for it.
Imo, there's no shame in getting orthodontia just because you prefer that aesthetic or really don't like the way your teeth currently are, either. None whatsoever.
The solution to the existence of an arbitrary beauty standard is not "well, everybody who does fit that standard actually looks creepy/[insert insult here]".
I think this is akin to saying something like: women should never have to wear make-up or suffer judgement for choosing not to wear it, therefore women who do like and wear make-up are bad and it's okay to insult and make fun of them and their choices about their own personal appearance. Or that because women shouldn't be required to wear pink or dresses, we should shame those who do wear pink and dresses. Or that because people should not be insulted for being fat, it's therefore okay to insult people for being skinny. It's a ridiculous way of thinking and doesn't solve the original problem at all.
And it just makes a situation where people can't win no matter what they do - crooked teeth, or no make-up? You get insulted. Straight teeth and make-up? You get insulted in a different way. And as always, everyone who isn't cis, white and male will have their appearances nitpicked this way the most.