My guess is the prosecuting attorney would point out that all hunters are subject to the Constitution of the State of Colorado. Then he would direct the court to Colorado Statute 24-33.5-704, which covers the governors emergency response powers. It states in section 2, "Under this 7, the governor may issue executive orders, proclamations, and regulations and amend or rescind them. Executive orders, proclamations, and regulations have the force and effect of law."
The Constitution goes on to say in part 7 that the governor may, "Suspend the provisions of any regulatory statute prescribing the procedures for conduct of state business or the orders, rules, or regulations of any state agency, if strict compliance with the provisions of any statute, order, rule, or regulation would in any way prevent, hinder, or delay necessary action in coping with the emergency;"
From there, claiming ignorance of the law would be fruitless. The defense could try to argue that the Covid-19 pandemic did not meet the criteria of an emergency. But IMO, they would lose that argument.
I'm not saying I like that governors have this much unilateral power. But, this concept is in the Constitution of most states.