The US fail to understand humour
I read the transcripts of the event and my first thought was that the speaker was taking the piss - the idea that it was someone nearby didn't occur to me, but it does feel eminently possible. After all, if I heard the crew of one of the most potent warships on the sea today seemingly fill their pants upon the approach of an unarmed bright blue speedboat I'd be inclined to take the piss too.
In addition, I do find it hard to reconcile the "if Iran starts anything we'll wipe them out" rhetoric with the "oooooo a speedboat we're all going to die oh noes !!!! quick shoot first they're so dangerous !!!111eleven " comments.
To be fair to the USN, maybe the two Iranians had really, really dangerous beards ?