My gut feeling is that, for reasons I laid out in Trump Declares War on the Administrative State, Dellinger's case is much closer to the Consumer Financial Protection Bureau case that resulted in the protection given that agency's director being tossed than it is to the safe harbor of Humphrey's Executor. Dellinger is not in charge of a "quasi-legislative" or "quasi-judiicial" organization; he wields quintessentially executive power, and to insulate him from the chief executive of the land is unconstitutional. In his dissent, Gorsuch basically said there was no legal way to reinstate Dellinger. But as Jonathan Turley said, a majority of the Supreme Court would rather this case go away than rule on the facts it offers.