Of those four results, the first one is explaining why they don't want author names in titles, the second one explains why they like minimal design, the third one was a false positive on "attention-grabbing Unicode glyphs," and finally the fourth one actually talks about the topic at hand. Why not just link to that one?

The fourth one places a lot of emphasis on the specific implications of "tl;dr" as opposed to other terms like "summary." Given such precision, I'd say the macroexpansion of "tl;dr" would be "too long; didn't read" since that's what it actually stands for.

I'm persuaded that "tl;dr" is best avoided. I'm not persuaded that my comment would or should fall under this guideline.