Put briefly, researchers blasted guinea pigs with 102 decibels of music for 4 hours. They found that while both the compressed and non-compressed test tracks caused temporary damage, the compressed variant made the damage longer lasting, suggesting that there's more to ear damage than just the loudness.

From this, what I would take away is not necessarily that compression on its own is harmful but that... there's almost certainly more to ear damage than just the loudness, and compression is one way this can exhibit through. So I'd say the title and angle of the article is a bit misleading.

Naturally, when I say compression I mean it in the audio effect sense, as they do in the article.