Do it the right way or don’t do it at all! If the 14th can be nullified by executive order then any other can and there’s a couple I’m pretty partial to.
He’s not attempting to nullify the 14th with EO, just clarify and revert it back to its original interpretation.
But, that is a matter of opinion. What if the next democrat president and his supporters say he is just reverting the 2nd amendment back to what it used to mean and that is different than your opinion on the issue? The separation of powers is there for a reason. The executive can’t interpret the constitution. That is the job of the judiciary.
The 2nd amendment has historically meant what it means, except for a period in the 1900’s leading up to 2008. They could technically try that, but there are dozens of instances where a citizen’s right to bare arms has been upheld versus a militia interpretation of the 2nd.