More to the point, as I note in another reply, you don't want to be *the lineman down the road with his hands on a "dead" wire*.
Pretty much the *first paragraph* in NEC 700 (700.6) says this:
""" Transfer equipment shall be designed and installed to prevent the inadvertent interconnection of normal and emergency sources of supply in any operation of the trans- fer equipment. """
So, if your transfer switch is *physically* capable of connecting your genset to the incoming power wires, then it violates 700.6, unless you're in a cogen sort of environment, in which case you're following Article 705, and a whole different set of rules apply.
You didn't keep reading. Or, you don't have the annotated version :) "Transfer equipment and electric power production systems installed to permit operation in parallel with the normal source shall meet the requirements on 700.5" This is from 2008, but I don't recall a change in 2011.