Yes as opposed to:
Failure on the pad=F,
Failure at altitude= F— (as it would kill many),
Failure before Max Q=C,
Failure after Max Q=C++,
Failure after separation=B,
Failure after achieving orbit=B++
Successful booster landing A
Successful StarShip landing A++ and everything about space ventures changes instantly.
I agree with your grade, with the caveat that apparently clearing the pad was the requirement for success.
I think you may have missed the joke, though. Oh well ...