For those unaware of the backstory there Musk recently had a major reveal of SpaceX's StarShip program. Bridenstine made a pretty direct jab the night before saying "I am looking forward to the SpaceX announcement tomorrow. In the meantime, Commercial Crew is years behind schedule. NASA expects to see the same level of enthusiasm focused on the investments of the American taxpayer. It's time to deliver." [2]
That was generally not so well received, since SpaceX is engaged in Commercial Crew (the program to get astronauts to the ISS on commercial launches) but so is Boeing. And SpaceX is substantially far ahead of Boeing on this front. So it felt like a partisan and biased sleight since Boeing, who went unmentioned, has substantially more political influence and clout.
In the Q/A Bridenstine acknowledged he was not really correct on his assumption, which makes me like this guy even more (as he does genuinely seem heavily driven to get the American space program back on track) - even if I think he should have figured this out before racing to publicly Tweet. Looks like he genuinely wants to get Commercial Crew going ASAP and was worried that SpaceX was putting it on the backburner since StarShip is also a really big and extremely ambitious program being done at the same that as Commercial Crew.
[1] - https://www.pscp.tv/w/1OyKAengZAMKb
[2] - https://twitter.com/JimBridenstine/status/117771110630074777...