Great, since we are all in agreement, let's see if we can put it clear terms.

Administrative warrants are civil in nature and do not give authority to enter a house or any private space. Using them as such is in violation of the fourth amendment.

An administrative warrant is just an email from their boss telling them to do it. It's not a real thing

Has this ever been tested in court?

What would that even mean? You present the judge an email from your boss and ask "Your Honour, is this an email from my boss?"