Earlier quoted context omitted.
Is it actually illegal if it's the pet project of the president, who has been given absolute power by the rest of the government?
Congressional inaction isn't assent. The Constitution clearly and explicitly gives the power of the purse to Congress (and this is also the understanding of I think Madison in the Federalist Papers and the interpretation we've had for now almost the entire history of the US so there's no reasonable dispute of this). Until Congress passes a law allowing this the president is constitutionally obligated to take care of…
personally I think this was Gödel's Loophole