I can't speak directly for Sal, but it may be that the knife fell partially into the marketing black hole that the Civilian and Matriach dwelled in. These special pieces were deliberately kept low profile.
Another thing to consider is the failure of the Spyderhawk sprint run (PE blue) which eventually went into liquidation (I believe). Given that the original knife run was special ordered for non-US distribution, that market failure would likely lead to no further manufacturing runs just for the general market, and I don't think that the foreign distributor ever ordered more.
Also a personal impression from talking to Sal back then, was that it wasn't really a full production model. it was a special order, with some released to the US as a favor to the hawkbill collector, and a market test to see if it had wider appeal. The collector's market likes them, but the collectors market is not and never will be large enough to justify production of an FRN model with its larger manufacturing runs. The Superhawk may suit this market better, the same way we hope the Caly III will keep the collector happy, without needing the volume sales required by FRN models. And of course collectors tend to prefer fancyscales and locks to frn.