Have you tried running
THING="~/Applications/SageMath/" xattr -rd com.apple.quarantine $THING -- You received this message because you are subscribed to the Google Groups "sage-support" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-support+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/sage-support/aba1daec-0585-4518-bb37-07b99f83f966%40googlegroups.com.