If Lord Mycron is on HMS Titan and Titan rolls a 5 or 6 for an extra action, does she now have two actions Lord Mycron can give away?
Mycron’s effect occurs instead of giving the ship any actions for the turn, so you only get the one no matter how many others the ship (or its other crew) could potentially generate.
He’s mostly wasted on the Titan, unless you’ve got some other ship in your fleet that absolutely needs that additional action, but even then you’re still far better off putting him on some other, less-valuable ship.