I'm sorry I wasn't clearer.
I don't believe it is because during the Apostolic Era and immediately following Christians worshiped on both Saturday and Sunday. I was injecting into the discussion that the controversy probably really got started because a pagan emperor set a day of worship for Christians.
a pagan emperor set a day of worship for Christians.
You should research that more fully for accuracy. It's akin to saying the British Parliament set the Westminster Confession of Faith.