Yours is a typical story, jonkster. Typical damaging Avmed overreach where all that was achieved was the imposition of stress and cost on you, for no substantial change in the objective risk to the safety of air navigation. Feels good to be an Avmed guinea pig, doesn't it? And I'll bet my bottom dollar that your circumstances don't count as a 'refusal' for the purposes of the statistics that CASA dishes up.
I've been there, done that. Avmed only backed down when there was the prospect of them being embarrassed about their decision based on "psuedo-science". Not my word, but that of Australia's foremost expert in the field. But when we're dealing with an organisation which lets smooth
PR folk play amateur nephrologist at Estimates, we shouldn't expect much more.
You are correct on food poisoning. And - yet - there is not a single sentence in the complex, convoluted and ever-growing regulatory mess that deals specifically with the service of food to crew before and during duties. That's because a ham sandwich and an orange juice don't look scary.