the president could just fire any AG he wants and replace them with whoever he wants ( in order to get a Special prosecutor replaced)in order to avoid impeachment . (similar to what happened in the watergate case)
I'm sure no constitutional attorney, but it seems like firing AG's without congressional approval would violate the separation of powers
maybe that's what the White House lawyer meant when he said it was a courageous act to remove Walpin
They were Inspectors General not AGs - but I believe your point is valid nonetheless.