While not useful to your immediate circumstances, I do think your case is an example of why we need a passenger bill of rights, similar to EU on specific compensation for such delays.
Rose Harman, speaking on behalf of Hawaiian Airlines, referred to the airlines CoC. No where that I read says $100 is the compensation you would receive. This, along with data points from other airlines under similar circumstances, suggests inconsistencies across the airlines as it relates to airline-induced delays, and more relevant, unregulated free-will to do this again and again with little repercussion. Obviously a history of this will result in bad PR, but an 8 hour delay could be 18 or 28, and the same outcome could be the same.