No it’s not it if it was this argument would have been made when past Presidents did it but it wasn’t. This is yet another example of people pissing their pants over Trump doing something past Presidents have done outrage of convenience is no outrage at all.
No single past President HAS EVER appointed a temporary AG that had not already been given the advice and consent of the Senate.
There also is a law in place, that is specific to the AG's position that Trump's lawyers are ignoring, which gives the specific succession of the AG position while in wait for a new AG if the current AG resigns,
The Deputy Attorney General
and the Solicitor General
etc....
This law has the succession with these 2 positions and 1 or 2 others as a choice for the president to use in a temp position BECAUSE these positions also are required the advice and consent of the Senate so these replacements are already cleared, under the Constitution..
Trump took an Act for the replacement of GENERAL temporary administration positions and has tried to replace a SPECIFIC rule of law for the AG position, a PRINCIPLE position, but the replacement act was NOT for PRINCIPLE positions being replaced... it's for other admin positions that do not report directly to the President.
The Constitution is VERY CLEAR on this.... his lawyers, are idiots and trying to do something unconstitutional and unlawful.