Unfortunately I don’t have a lot of faith in Blue Origin. They have only built 9 BE-4 engines in 10 years. None have actually flown anything. Spacex has built and tested over 100 Raptors and flown 5 Starship test flights. 4 of those crashed on landing but the engines worked.
Yes, that’s what’s holding Vulcan back. I wonder if ULA is regretting not going with the Rocketdyne offering.