Because he was at stadium and Warnock has worked with him - it was a bit of mutual respect - Warnock knows what Mr Durham does for a living - no doubt he's sat in on production meetings when he worked there so knows damn well how it works
It will be back to his usual self today but that's what they all do on that radio station - if they were constantly complimentary they wouldn't get Mr Outraged from Carmarthen/Burgess Hill who has been a Liverpool/Man Utd fan all his life ringing in to demand the sacking of their manager