Unsolicited critique is almost always unwelcome critique, in my experience. Especially where someone else's 7 year old is concerned.

Respectfully, if you see the comment as critique, that’s on you. It could just as easily be described as “unsolicited advice” or “unsolicited tips”.

The communicator does have responsibility on how their message comes across, thought not all of it. It’s on the receiver to also make an effort to understand what was meant and not take unnecessary offence. The comment reads pretty much neutral, apart from a post scriptum which is explicitly about the author’s preference. It’s up to you to inject the writer’s feelings as either “this code sucks, here’s how you do it” or “congratulations on making something cool, here are a few suggestions”.

My experience is that life is much better if you take the latter approach. Default to empathy.

Consider listening to “This is Water” from David From Wallace.

https://www.youtube.com/watch?v=eC7xzavzEKY

Let's agree to disagree. I most certainly didn't take offense. I just disagreed (and continue to disagree) with the (your) comment that I responded to. I'm sure the parent of the 7 year old in question was aware of the shortcomings of the code. The fact that a (presumed) grown-up read the post/thread and their reaction was to provide a code review is odd to me and more than a little hackernews-ish which the poster you responded to poked fun at and which you seemed to take exception to.