I think if the intent of the speaker is to answer a question and they can be understood reasonably well, but their English is not perfect, then we should give them some slack.
I appreciate the spirit of the parent, but I think even that message starts with the wrong premise. It assumes that the group with high proficiency in English ("we") decides whether or not to welcome others with low proficiency ("them").
In fact, the commenter several levels up is as much a member of HN as you and I. The guidelines for contributions are not about English proficiency, but about intellectual value. We want more members making more valuable contributions. If they misspell every word and break every grammar rule, it doesn't matter as long as I can understand them and the comment contributes something.
What is outside the guidelines is one commeter criticizing another's language, especially using words like "atrocious". That comment contributes nothing of intellectual value to HN.