No I'm looking at it also and came to the same conclusion.

I'm currently looking at the available export option kExOptCodeSCALEFACTOR, trying different values.

Oh and just this minute noticed that kImOptCodeARMALIGNMENTAXIS is an import option ont an export option so should be removed. I'll try that now.

I really don't want to write the BVH file from scratch because I'd have difficulty justifying the time for a freebie.