He deserves a crossover with Evil Nazi Patrick Troughton.
"Hail to the Chief" is in the public domain now, but perhaps it wasn't in 1969? They might have been playing a different tune from the 1800s time when Space Lincoln arrived on the Enterprise, but "Hail to the Chief" has been the presidential anthem since before real Lincoln became president.
Also, was it just a trick of the lighting, or was the actor playing Space Lincoln practically in brownface during some scenes?