Where it will be consumed by the mold eating cave inhabitants. Do they really think that cave ecosystems weren't prepared for a deer carcass? They had received external supplies of nutrients for millions of years.
Keeping caves clean is a good thing, but if people can't behave can be fined for it. In any case, regular cleaning teams should be included in the budget of the park as part of the management. Stop being cheap with nature.
Except for the aluminum and plastic bag, easily removable, this is a storm in a teacup. Would be relevant only when prehistoric art is present.