It makes perfect sense. No, we probably wouldn't use assets sitting off the Florida coast that we would use to strike targets in Asia......but it makes perfect sense to demonstrate that we can hit targets in Asia from the Florida Coast...from a submarine.
And then look to the context this is being discussed. North Korea had threatened Guam...then PJL was mentioning NK would target the American data collection center at Pine Gap in central Australia. Sending a missile test from the Florida Coast shows Asia, indeed Russia, China, and the rest of the world that we can launch an ICBM.....from a submerged sub....have it travel in excess of 7000 miles.....and hit a nail on it's head. We can do this in the absence of a functioning Guam and/or Pine Gap, NK nor anyone else can hope to degrade our ability to strike from anywhere in the world. And strike accurately. Makes perfect sense.