i dare say - there are a lot less people that can build biodomes on earth - than battleships.
sure you can build a steel glass construction and plant a seed - maybe you even get a tomato out of it - but its a long long way to a working and independent ecosystem which is in balance with itself - and also efficiently producing food.
look at it like that - on earth - there are countless people who managed to build large ships with cannons mounted on top of them.... but there is NO man who has yet managed to build a biosphere. - both US projects were failures - while the same country manages to build big ships with cannons.
there was once a great warrior who had learned the way of combat in all its ways. - he was learned in all kinds of weapons - and was never defeated in his life. .... but he was a terrible cook.
just cause you can build battleships doesn t mean you know anything about genetics or plantlife and food growing. - and i dare say.... sticking a seed into the earth and waiting for the tomatoes to grow is what synth food may call "an optimists garden" - but if corsairs do it the way you describe it ... no wonder they all starve =P