Robert Mueller realized that Donald Trump's nature and behavior were intrinsic to his identity as president. Instead of trying to argue against Trump's character, Mueller acknowledged the futility of doing so, as it was an inherent part of who Trump was. This acceptance highlighted the circular reasoning that surrounded any critique of the president, as his qualities were both unchangeable and a source of support among his voters.
Ultimately, Mueller found himself aligning with the perspective of the White House, recognizing that Trump was the president and that the public had voted for him despite, or perhaps because of, his defining traits. This situation left Mueller seemingly resigned, as he understood that the reality of Trump's presidency was that it was characterized by his straightforward and often controversial demeanor.