Do manufactures list the maximum speed of an aircraft based on its theoretical maximum speed or dive speed?
The 365 knots listed in that brochure is (as noted in the text) the maximum cruise speed. That is the maximum speed at which the aircraft can be expected to operate under normal circumstances in level flight. It is not related to the Never Exceed speed, which depends on the structural limits of the aircraft (as well as air pressure and atmospheric conditions etc.). The maximum cruise speed is interesting for planning purposes, as it gives you an indication of how far you can expect the aircraft to go in a certain time window. It is not, however, very interesting to pilots, who will operate the aircraft with regards to the actual structural limits.