Grain access in Rome was political power. The tribune who controlled distribution controlled the mob; the general who secured Egypt controlled the republic. This proposal focuses not on the economics of the annona but on its constitutional and political ramifications - how grain policy shaped the power of the tribunate, contributed to the Gracchan crisis, and may have been a proximate rather than merely contextual cause of the republic's collapse.
Agreed on Sicily — I compressed the timeline in the description. The Egyptian point is more about the late Republic specifically, where control of grain became inseparable from control of the eastern legions. The Gracchan section would focus on the lex frumentaria and its constitutional implications rather than geography.
The Gracchan crisis framing is compelling. I'd push back slightly on treating Egypt as the decisive variable - Sicily was the primary supply source for most of the Republic and the Egyptian connection only became politically crucial after Pompey and then Caesar. The chronology matters for the causal argument.