JMHO, Trump considers the EO/National Emergency route to be not-quite-within-the-bounds when he's spent so much time/energy on rebuilding trust in the Rule of Law and the rest of the Process of Governance (which the 'rats/Obama have been raping and pillaging at every opportunity).
It would certainly be quicker and more effective to simply wave at Obama's crass indifference to The Law as justification for "curing" something, but then only find that along with clearing up a symptom, we've multiplied the lack of trust/regard for the Law and Governance which is the actual affliction.
Might take a little longer to do The Plan this way (and Lord knows at my age I'd like to see it expedited) but outside of praying I'll just put my trust in The Lord, Trump and The Plan and stand by.