Today " don’t (or never) look a gift horse in the mouth" means don’t find fault with something that has been received as a gift or favor. Don’t be ungrateful when you receive a present, even if it’s not exactly what you wanted.
Ah! sir, I do indeed. It is a grievous affair to my poor girls, you must confess. Not that I mean to find fault with you, for such things, I know, are all chance in this world.
Its defenders retort that it aims only to help the federal government fulfil its obligations on immigration, and that only an administration that was deliberately neglecting them could find fault with it.