Huh - I'd just assumed that the ship was rad-shielded but you're right.
However having a ship that can't fire its main weapon without hospitalising half the crew is really very dumb, even for Drinax; so for my campaign I'm not going to do that. I'll say the design is clever enough that the crew-spaces are shielded from the big gun. Of course if they mix it up with a Gazelle then things will get interesting....
Failing to spend 25KCr per dTon for rad-shielding on your multi-MCr vessel is a really bad design decision if you frequently encounter weapons with the radiation trait, so I guess neither the Imperials or the old Star Kingdom forces expect such weapons to be common among the typical adversaries for these classes - Harriers and Gazelles are both small ships that are intended to be used against armed civvies rather than real warships, so that makes some sense I suppose.