Because merely calling it a Muslim ban removes any plausible deniability and exposes the government to all kinds of legal challenges.
If the government wants to do some bad or unethical, they won't be straight about it. They will use euphemisms and "newspeak" to disguise their intentions (e.g. "enhanced interrogation").
It's akin to parallel construction. Start with the party that is presumed guilty, then work backwards to change your actions and arguments so that you can still persecute the party but without obviously breaking any laws.
If the government wants to do some bad or unethical, they won't be straight about it. They will use euphemisms and "newspeak" to disguise their intentions (e.g. "enhanced interrogation").
It's akin to parallel construction. Start with the party that is presumed guilty, then work backwards to change your actions and arguments so that you can still persecute the party but without obviously breaking any laws.