I attended this conference too.
Though his tone was painfully angsty, I thought the intent of the irate attendee wasn't overly objectionable. The speaker kept referring to the block list as opt-out DNS-based blacklisting that ISPs can choose not to implement. But that doesn't fit with the non-UK ASN IP address phishing blacklisting capability that was mentioned almost in the same breath.
What's even more interesting is the NCSC's admission of a(n automated?) capability to identify these non-UK hosted phishing sites. The paranoid infosec bod in me thinks that the NCSC is whitewashing GCHQ's bulk interception programmes and is hoping that reaching out to the technical community will win hearts and minds.