Why a Linguist?
Why did they have Daniel in SG 1? because there are many different languages out there, and you need to talk to others. So say they find an alien species ( this time the Krell) He/she would work to read the language. So as a science vessel, that would be very important, but also useless if they don't find anything for them to study.
They weren't expecting to meet anybody there, plus the Krell had been dead for (I wanna say) a million years.