Grammar police: FEWER than half is correct.
You're treading on thin ice. 'Fewer' generally refers to a value that can be counted. "Half" can't be counted. "Fewer scientists" CAN be counted. You didn't even include "scientists" in your quote. I think you're dealing with a technicality that most followers of Her "Queen's English" would ignore. I'm not sure you're even correct, and to me, it's not even worth looking up.