If there are "no round trip awards what-so-ever," as Happy pointed out, why is it that the HNL->MIA will be cancelled if there is no MIA->HNL?
Because any one-way AA itinerary (and all AA awards are one-way now) must be flown in the exact order of the airports/dates booked. Thus, the HNL-MIA leg
must be flown before the MIA-TLS leg. Somehow they have to get themselves to HNL (by plane, boat, or kayak

) so they can fly the HNL-MIA leg before the MIA-TLS leg, or the whole HNL-MIA-TLS ticket will be canceled.