So you contend that the authority of the Sgt at Arms is confined to DC, is that correct?
Absolutely not. The law supports it in certain terms.
The practical reality of performing an arrest outside of DC is another matter entirely.
It's not going to happen, no matter your insistence it should.
Hell, if I was world ruler I would insist on it too!
The enforcement arm of the Congress, when it comes to criminal law is, at BEST, feeble. In reality, non-existent.
However, our feckless Congress does have far more powerful weapons which they choose not to wield.
Funding.
Impeachment.
And for that they belong in the Hall of Shame of all future American History books...if we ever see any more such books.