The Ibrox striker remains suspended for the next four European games.
Rangers assistant boss says clashes between heavyweight clubs would lose their sparkle if they became regular occurrences.
SPFL chief executive says proposal would 'dramatically undermine the global appeal of football'.
Centre-back Ondrej Kudela was accused of racially abusing Glen Kamara when Slavia Prague beat Rangers at Ibrox.
The Scottish FA says it intends to complete the cup matches in front of supporters.
The SFA and SPFl have taken the decision to cancel all games with immediate effect.
Concerns have been expressed about major sporting events being held this year.