“One of the hostages is a Klingon” is not a reason the Federation will be sending a rescue ship of its own. The Klingon is probably an exception to the reason the Federation is sending the rescue ship. They probably wouldn’t specifically seek to rescue a Klingon, but they would send a rescue ship for the others. Still, given the context that there are federation people among the hostages, one can conclude that the Federation will be sending a rescue ship.

The full exchange was inappropriately clipped in that example, which is why I didn't reply to it here.

Vixis: tlhIngan ghaH wa' vub'e'.
Klaa: latlh?
Vixis: wa' tera'ngan je wa' romuluSngan.
Klaa: vaj toDDujDaj ngeHbej DIvI'.

Klaa was replying to the news that one of the hostages was a Terran, not that one was a Klingon. In this case, because of this reason could actually be used here if we didn't already have vaj.

I still find the use of meqvammo' extremely clumsy, however. It often doesn't make sense until you squint at a sentence long enough to realize that something has been presented as a reason for something else. With vaj, on the other hand, you don't have to recognize something as a reason. You just have the cue that the sentence is a conclusion of some sort.

-- 
SuStel
http://trimboli.name