Our speaker sits. He looks, remembers, imagines, and thinks. He's just about the least active person you can imagine. Even the memory he drifts into is of watching planes. There's no doubt about it—the speaker of "Reading Moby-Dick at 30,000 Feet" clearly seems bored and discontent with his passive position. The contrast between his passivity and the action in Moby-Dick (and his desire to be part of such action) is pretty much the central tension of the poem.
The last line tells us that our speaker's longing for adventure is not in fact a longing for control. He still wants someone else to direct him (the captain), so we understand that his dislike for passivity has to do with his desire to be physically active and engaged with the world around him.
The speaker's passivity is his own fault. He could be a whaler if he wanted to.