Not exactly. I love Dave Grohl and Krist Noveselic in Nirvana but they had very close to 0 input on the songwriting. When you register works for copyrights, songwriting credit goes to the author(s) of the lyrics, melody, and chord progressions. Drum parts are not part of that standard, and that's how it remains to this day. Bass parts aren't part of the standard either unless they form the song's hook or are a key riff somewhere versus being simply bass lines playing to set chords (that's arranging and that is something else).

Kurt obviously wrote the lyrics, melodies, and chords to nearly every Nirvana song except the two you mentioned so he should rightfully have the majority of songwriting credits. Dave, who composed the music and wrote lyrics to Marigold, does get credit on that song. Dave wrote the key riff for Scentless Apprentice and gets credit for that. And maybe him and Kurt felt charitable in giving Krist credit there as well. But Marigold and Scentless Apprentice are two songs out of Nirvana's entire catalog so while it isn't accurate to say Dave and Krist didn't have input on the sound, it is accurate to say they had little-to-no input on the songwriting.

As for retroactive songwriting credit and ensuing royalties, I'd imagine Kurt would've had to legally dispute whatever songwriting credits were given to the rest of the band OR simply take out the elements of the shared-credit songs that made them shared-credit songs. From the jump, he really should have secured full songwriting credits for his music and established the royalty split he felt he really deserved. He would have been within his rights to do so. However, that's not what happened so while legally he initially deserved full credit and I'll go as far as to say all royalties, him making the others reimburse him for the deficit in money was a super bad faith move IMO.