Should Twitter ban such comments? Reasonable people could go either way. But for the specific individual making such comments the resoundingly correct answer is

Should Twitter ban such comments? Reasonable people could go either way. But for the specific individual making such comments the resoundingly correct answer is they should be ashamed of themselves. And for that specific individual the free speech implications are that the more folks who speak like them the less appealing free speech looks and the more at risk free speech begins to look. Why has Twitter been pushed by the Public to moderate and ban people? Because there are enough folks out there willing to make those kinds of comments on their platform that it starts to look like an existential risk to the company. As to ridicule, it rarely if ever causes someone to improve. You'll be much more effective at getting better more efficient code if you instead play the role of mentor or helpful hand.