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Now that Chevron is no more, EOs are even weaker than they used to be because the regulatory agencies no longer have teeth.
Premature compliance != legally required compliance. Anyone complying early to an EO when they don't have to is an idiot.
For the more egregious ones, there are temporary restraining orders... days/weeks/months later.
So, yes, he can do that, and yes, he can be overruled on them, and yes, that happens after some damage has already been done.