His default reaction to having his views challenged, on any issue, is that it is up to the other person to prove him wrong. Even if his own initial stance took next to no thought to arrive to.
It's like if he feels something to be true, then therefore it is true, and he will assert so much until someone else challenges him sufficiently to change his mind. No burden on him to think things through thoroughly, do some research, crunch some numbers till he comes to his view. Nothing whatsoever. And he'll defend that viewpoint till the end.
When challenged, he could just say 'well yea, I've put next to no thought into this, you're could be right'. No. Instead he puts pressure on whoever challenged him to prove him wrong. On a stance he's taken after next to no thinking about it. Because to him, it's not his job to justify his claims. It's up to everyone else to explain to him why his claims are wrong, or why his opinion is flawed. He's not putting in any work to arrive there, yet we have to put in all the work to shift him from that.
It's remarkable.