Um...Mendez was never really there. If the Talosians had contacted him or other Starfleet or Federation personnel, it was probably after the ruse had already taken place. If they'd been convinced beforehand, the general order declaring Talos off limits would have been waived without having to go through the charade.
Mendez sent the Enterprise a message which Uhura received right after the Telosian flashbacks were completed. Mendez was receiving the same images back on Starbase 11 and immediately sent out the waiver mentioned.