"There are practical issues, too: Musk has a reputation for overpromising on timelines. SpaceX has never launched anyone into space. The Falcon Heavy has never flown. Moreover, NASA officials would be unlikely to embrace a SpaceX moon flyby unless it clearly fit into the agency's long-term plans for deep-space exploration. What does Elon want to do with this - is it just a one-off tourist flight?" said NASA's top official for human spaceflight, William Gerstenmaier, in an interview with The Washington Post. "I don't see it as advancing human presence in the solar system."
Keith's note: NASA has never launched SLS and has never put people into space in Orion. SpaceX has launched (and recovered) multiple Falcon 9 rockets (the components of a Falcon Heavy) and has sent multiple Dragon spacecraft to/from the ISS on those same Falcon 9 rockets. SpaceX may have delays but they always deliver what they promise. NASA doesn't have as good of a record in that regard. With regard to lower cost, reusable spacecraft flying around the Moon - without NASA funding - such as SpaceX is planning to - if Bill Gerstenmaier doesn't "see it as advancing human presence in the solar system" then he really should relinquish his position at NASA to someone who understands what is going on these days. Indeed, Gerstenmaier is going to have a very hard time fitting in with what the Trump folks want to do if he continues with the antiquated mindset he is so fond of promoting.