Article 600.6 ask for a disconnect for a sign. If a sign builder installs a switch as an integral part of the sigh does this satisfy the requirement? One must realize that the UL standard does not require a disconnect as part of the requirements for sign construction.

If it was at the circuit entry into the sign, disconnected all ungrounded conductors and was marked as the disconnect with an "off" position I would allow it.

yes a factory installed disconnecting switch that disconnects all ungrounded conductors is allowed

I guess I left out a very key point. The branch circuit enters the back of the sign enclosure, travels through the sign and then exits the sign to terminate on the line side of a WP switch mounted on the sign. The load side of the switch has conductors that re-enter the sign enclosure and connect up to the Xformer of the sign. I feel that this a violation of 600.6 since the switch does not disconnect all un-grounded conductors in the sign. What do you think?

Note I said "at the circuit entry into the sign". I agree with you, either move the disconnect to the conduit entry point or change where the conduit enters to make it next to the switch, preferably in a separate enclosure within the sign.
This could be as simple as a 4x4 deep ring that covered the switch terminals and conduit entry with a blank cover on the other side.
I believe the purpose of the disconnect is to make the interior of the equipment safe. I am not making a proposal but I do think a label over the disconnect enclosure saying something like "line voltage present with disconnect off" is a good idea.