[adolph]

> do the stack of paperwork for crew rating the combo of Starliner and Vulcan.

Or/and Falcon 9!

Starliner is designed for compatiblity with . . . Falcon 9, and Vulcan Centaur.

https://en.wikipedia.org/wiki/Boeing_Starliner

[dotnet00]

Putting it on Falcon 9 would not be ideal since then you're back to having a single point of failure in terms of preventing crewed launches by the US. Plus, considering that they don't exactly like SpaceX, while being half of what formed ULA...