There are mitigations (of a sort) for the Starliner. It probably should not have launched, but now that it has, the flight crew is no longer in danger and can be brought down via Crew Dragon if necessary (as if Boeing needs any more embarrassment). If I was NASA, I'd take that option; though actual danger to the astronauts coming down in the Starliner seems minimal, having SpaceX do the job just seems safer.

As it is, NASA is keeping the Starline in orbit to learn as much as possible about what's going on with the helium leaks, which are in the service module, which won't be coming back to earth for examination.