I am aware of the 2003 attempted revision and the first sentence of my post briefly addresses that point. To go more indepth we require a separate thread as this is not the main subject of the original topic. However, IMO the reclassification did not go through simply because there was no monetary incentive to get others to agree. In fact there was quite the opposite as it was a high value commedity and keeping it's classification simplified to a singular species (scleropages formosus) allowed it's native countries to control:I'm not talking about aus-indo crosses, I'm talking about the fact that reds, golds, greens, and the other one would've gotten their own species, splitting them from s. formosus (sp. nov would've been s. aureus, s. legendrei, and s. macrocephalus). Seeing as people regularly breed these together in captivity, if all the wild colors were officially elevated to different species, then their crossed offspring would then be considered hybrids, and not covered under any conservation laws.
1) the destruction of the native habitat & conservation of native populations
2) tax collection of a multi-million dollar industry
Post 2003, around 2010 IIRC AFAIK, it's been proven that the reclassification was unnecessary as the different color genes, more specifically the haplotype, were found within different scleropages formosus that would've have been different species had the 2003 reclassification gone through. There are critques that could be made since, as you said, if these were technically different species but already hybridized then the recent findings would in fact support the 2003 reclassification. However, that is a "chicken and egg" argument and the reality is there is no chance of a reclassification unless there are new unique genetic traits identified between the different color morphs. This testing would have to be done purely on wild specimen but it wouldn't matter; the environmental degredation of native habitat will make CITES never lower the classification from Appendix I. Even if a reclassification did occur this would mean for a brief 1-2 week period you may have "legal" asian arowana but CITES would quickly reclassify it's listing to match the new species and the US would still uphold it's current standing similar to when scleropages inscriptus was identified. Would you risk several thousand dollars on a chance of not having your animal taken in by customs or getting a visit from the feds? Hence why an Australian x Asian hybrid would be the only real hybrid chance at owning an asian arowana if it is possible.