I love John Piper and have gone to his church many times, but this is theologically unsound, and inconsistent with Piper’s usual thoughtful, solid Christian witness.
It might have been an expression of divine disgust. We have too little information to say that it positively is.
I disagree. When folks asked Jesus about the meaning of certain disasters He quite explicitly said that they happened as examples to us all, and that so would we all likewise perish if we don’t repent.
Things happen for a reason, and we should all take the appropriate warning from them.
God calls homosexuality an abomination, and I’m sure you’ve read in the Scripture how God always ultimately deals with such.