Yeah, I know some don't see it like that. He wasn't calling the fans a disease though was he? He was saying a Sunderland 'disease' exists. As
@Ozzymac says, that could have been a comment about the expectation levels or any number of other things. What he said is just an example of them not being very good at running the club. It seems to me that people who are offended by it are choosing to be offended because they want to be offended by him. It was just a stupid comment from a frustrated bloke.
People can choose to see conspiracy and spin and lies but it won't do them or the club any good. Or they can choose to be more level-headed about it and recognise that it's a couple of blokes a bit out of their depth, cut them a little slack, and give them space to run the club until they can sell it.