That is not what the 5th amendment states.
I suspect that you are referring to this part of the amendement, “except in cases arising in the land or naval forces, or in the Militia, when in actual service in time of War or public danger.”
Our muslim friend was not in the armed forces, or in the milita, and so this language doesn’t apply to him. Apart from his not belonging to U.S. armed forces, this exception does not apply to the rest of the amendment.
Now to answer any argument that he was in a land force, this language does not generically refer to any armed forces, as first, the land and naval forces should be interpreted consistently with the rest of the Constitution, and Article I, Section 8 refers to “the land and naval forces” as being under the control of the U.S. Congress. Thus, “the land and naval forces” has to refer to U.S. forces.
It's all pretty clear.
Remember, to "repel invasion" the CIC has to have Constitutional Authority, so the 5th simply makes sure that pre-existing Constitutional power inherent in the job continues to be respected.
It's not like the Founders didn't know what they were writing about ~ bet you thought they were protecting the innocent ~