Why All Music With Halal Lyrics Allowed?
In reference to the study that you shared, please understand that correlation does not imply causation. Secondly, the study finding that you shared above about heavy metal music doesn’t exclude immoral music. The yardstick for halal and haram has been provided to us by God in Quran verse 7:33, and we should stick with that. If someone wants to be extra careful about something it’s definitely their prerogative.
He’s not saying to avoid certain tunes (dhun); what he’s saying instead is to pay attention to the words. If the words don’t have anything impure or immoral then there’s no absolute prohibition for any of the fine arts including music.