Because Trump has made loud claims the intelligence community is unreliable. That being the case, someone decided they couldn't just brief him, they had also to be prepared to school him in what an authentically unreliable intelligence looks like. As you say, it did not come down to that, apparently. He was, however, later shown the unreliable report, after the official briefing was over.I would like to know just who and why that person believed that this was a good idea during a factual briefing session about serious problems with Russia espionage operations with the top intel chiefs. It seems a very unusual element to have in the briefing folder during these types of circumstances.