The human flesh exploit is fixed. Now powdering human flesh makes soylent green. Something similar will probably have to be done to the other things. Probably just adding veggy to the material list will make it inedible for carnivores. Try eating fish makizushi, which has both the veggy and flesh material tags. Let me know if you can eat it as a carnivore.
{
"type" : "COMESTIBLE",
"id" : "hflesh_powder",
"name" : "soylent green powder",
"name_plural" : "servings of soylent green powder",
"weight" : 38,
"color" : "white",
"addiction_type" : "none",
"spoils_in" : 0,
"stim" : 0,
"container" : "bottle_plastic_small",
"to_hit" : 0,
"comestible_type" : "FOOD",
"symbol" : "%",
"quench" : -4,
"healthy" : 1,
"addiction_potential" : 0,
"nutrition" : 10,
"description" : "Raw, refined protein made out of people! While quite nutritious, it is difficult to enjoy in its pure form.",
"price" : 1100,
"material" : [ "powder", "hflesh" ],
"tool" : "null",
"volume" : 1,
"cutting" : 0,
"phase" : "solid",
"charges" : 4,
"bashing" : 0,
"fun" : -4
},