But it does.  It makes a difference as to whether the returns are correctly prepared.

Both NC and VA allows credit for taxes paid to other states only on income from sources without their own states.  If your client telecommunicated from NC and VA not for the convenience of the NY employer, the wages will still be sourced to the home state where services were performed, which means taxes paid to NY would generally not qualify for a credit (in spite of NY considering the same to be NY-sourced).

This is a well-documented conundrum that has been tried in courts and which should be avoided.