The flaw in this belief is that the president can make an immediate law by issuing either a directive or an executive order. These basically bypass the checks and balances written into the constitution and have the full force and effect of a law. The constitution originally set up controls where one branch of the government can overrule another by following its normal procedure. EO's and directives basically work outside of those procedures.
Very, very bad thing if used unwisely. I'm not even sure if a court can overrule an executive order, I need to research this more.