In my opinion, it seems that Messenger Supported Wiring is such a distinct wiring, it has it's own article in the 300 section of the NEC would say to me it is its own wiring method. just like romex, AC, Etc...
Multiplex cables utilizing a bare conductor, factory assembled and twisted with one or more insulated conductors, such as duplex, triplex, or quadruplex type of construction, is clearly one of the accepted type allowed in this section. no where does it state this manufactured assembly must use a conductor listed in table 310.13(A) the same way 334 does not require the individual conductors in NM cable? because it is a cable assembly. this is why it's not there. and also this is why it has it's own article in the 300's of the NEC. it is a manufactured wireing method that is reconized by the NEC as a factory assembled cabl just like romex, AC, MC Etc....
I ask this where are the conductors of romex, AC, MC cables listed in the table 310.13(A)????