You didn't search very well as there have been numerous topics on this created (and trashed):
https://bitcointalksearch.org/topic/2018-03-20researchers-say-16k-files-are-stored-in-bitcoins-blockchain-3169408
https://bitcointalksearch.org/topic/2018-03-20-cointelegraph-researchers-child-abuse-found-on-bitcoin-blockchain-3168058
Not to mention that these are not even relevant news, in fact : https://www.dailydot.com/business/bitcoin-child-porn-transaction-code/ that was from 2013. Those idiots in your article think they are the first ones to find something like that, surprise, they aren't.
OK Sorry hillarious. When I searched, it gave me the first results from January