You're doing it all wrong because:
1.- You can't hex edit an area based on an event. It'll always change.
2.- BNE dontdoshit: is wrong, just put dontdoshit:
3.- You can just omit the CMP #$00, it'll work fine.
4.- You're doing nothing if Player 2 is in play, and you want the patch to do otherwhise.
Try this, untested because lazy:
autoclean JSL spinjump1P
LDA $0DB3 ;\ if Mario, return
BEQ - ;/
LDA.W $148F ;\
INC A ; | restore old code (luigi)
STA.W $140D ;/
hope i did nothing wrong like i always do lol
e: today i learned asm
..or not, but my code doesn't work lel