Queensland Rail is not likely to setup a bus service just for the BICT. The buses are for use during track closures, stoppages and linking country towns. It would be impractical to have them unavailable for their actual purpose on cruise days.
I don't understand this insistence that the BICT has to be another OPT, with the facilities that the OPT has. It would be much fairer to compare it to the White Bay Cruise Terminal. Or even more appropriately to the Grain Terminal wharf across the river.
The OPT happens to be sited next to Circular Quay, the best public transport nexus in Sydney. Which was not built in order to service the OPT or even with the OPT in mind.
The BICT is not and never will be the OPT. If someone wants to run a bus shuttle service to there, I'm sure that Port of Brisbane would oblige. In the meantime if I want to catch the public bus, I'll walk to it.