1) There may be additional communications we don't hear; all we're getting is what the tower hears, which is not necessarily everything.
2) Aviation is, in large part by necessity, built around the concept of knowing who has authority to do what, and listening when the person with the authority gives an instruction. When the tower hears "airport is closed" from someone with the authority to say it, then the airport is closed, full stop. Arguing about "well, why is it closed" or "I'll close it when I check with my supervisor" eats time that can cost lives, so organizationally it's set up to avoid having that happen.
2) Aviation is, in large part by necessity, built around the concept of knowing who has authority to do what, and listening when the person with the authority gives an instruction. When the tower hears "airport is closed" from someone with the authority to say it, then the airport is closed, full stop. Arguing about "well, why is it closed" or "I'll close it when I check with my supervisor" eats time that can cost lives, so organizationally it's set up to avoid having that happen.