One of Donald Trump’s biographers sees the profits he scored through his hotels while president as cause for concern about blackmail or other forms of national security threats. Speaking to MSNBC on Thursday, Tim O’Brien explained that from the very beginning there were concerns about how Trump would conduct his business while also serving as president. While he claimed to be prepared to put his companies into a blind trust, he never did, and the profits rolled in. When doing business in Washington, foreign leaders stayed at the Trump Hotel, according to a House Oversight and Reform Committee …