I'm the actor in question who played that role and my sister just sent me the link to this site. First, as an actor, I was pretty stoked to kill two birds with one stone. To wear the Star Trek uniform even if not on the actual DS9 show and be on Hawaii Five 0 even if it isn't the original was pretty cool to have been a part of. Second, I'm glad you guys liked the cameo even if it wasn't the real Captain Sisko (Avery Brooks).
I knew the discrepancy between uniform,rank and dialog would be picked up by Star Trek fans and in as friendly and fan oriented a manner as I could, I said as much to wardrobe when I was getting fitted a day or so before the shoot and again to the writer on set. He actually looked mildly alarmed but by then however, it was too late and I'm not a big enough name to have all the lines flipped around to have me, a day player outranking their lead, Commander Steve McGarrett. No one wants to hear anything except dialog out of a day player.
They needed Steve McGarrett (Alex) and this character to both be commanders for the buddy banter to work. My take on it is something was lost in the communication when they asked for licensing permission from Paramount. A script was probably sent but not read and an authentic and may I say HIGHLY uncomfortable uniform was sent out and that was that. Also, due to licensing there was a set number of minutes my character could be on screen. An AD tried to throw me in later talking to some other con attendees and a producer walked (ran) over and nixed that pretty quickly.