Back in the 1950's, most businesses closed on Sundays. When businesses began to open on Sundays, someone is said to have warned, "if you shop on Sunday, someday you will have to work on Sunday." That turned out to be prophetic.
I see it that way... It just isn’t necessary. People can (and learn to) plan around when things are closed and it allows for time with the family which I think is extremely important. I think everybody loses, it isn’t healthy to be working 7 days a week. Parents need to spend more time with their children, not less. I wouldn’t eat out on a major Holiday, it only encourages it.
That said, Pizza Hut is within their rights to fire him, he must have known that could have been an outcome. The comparisons to military service, police, etc. are a little absurd as they provide essential services. This is pizza!! c’mon!