Really? They swear an oath as a condition of being able to hold their respective offices that they will.
'I (name), do solemnly swear (or affirm) that I will support and defend the Constitution of the United States against all enemies, foreign and domestic; that I will bear true faith and allegiance to the same; that I take this obligation freely without any mental reservation or purpose of evasion; and that I will well and faithfully discharge the duties of the office on which I am about to enter. So help me God.'
Merely disagreeing with a law is poor way to state his case. If a law is unconstitutional is he obligated to defend it? That then brings us to who makes the appropriate decision as to which laws might be unconstitutional (it is not the AG!).
This current regime just does not care what the law says, if it hurts their cause.
That absolutely doesn’t matter to anyone in this administration.