It'll contaminate because thermophilic molds such as Doratomyces spp.(Black Pin Mold), Trichoderma(Green Mold), Dactylium Mildew(Cob Web Mold) are all stimulated at temperatures starting at 80F. Which is why for all incubating 75-78F is ideal. Substrate temperature regardless strain of Cubensis is 83F for fastest growth but with jars, several degrees of heat are produced(a process called Thermogenesis). So, for fastest growth go 80-81F, for rye jars go 75-78F. Colonization speed is measured by moisture content, gas exchange, amount of inoculants, temperature, etc....
Wrong on the Bulk Substrate/Casings/Cakes They'll last as long as the food is still there. Once it starts giving off mutations after the 3rd or 4th flush, bury it 6 inches under in the garden.