Gary Juffa's comment comes after the Indonesian President Joko Widodo visited PNG this week as high-level lobbying intensifies over the looming decision on the MSG membership application.
Jakarta has indicated that other parts of Indonesia which have Melanesian stock should have been included in the West Papuan bid.
Mr Juffa says that PNG's government is likely to reiterate that the membership bid must be endorsed by Indonesia in order to be successful.
"And then what Indonesia will say so that it's not such a hard swallow, is that, hey, West Papua and Papua and this and that and five other regions will also be members.
“That's what they're going to propose. Then the MSG has just failed in its complete and purpose and agenda and should be disbanded."