So, the first contact and first ambassador sent to them are not seen or heard from again yet they open diplomatic channels?
Fascinating.
Actual first contact and first ambassador would make a good story by itself, or at least a good introductory chapter.
Imagine settling on a world inhabited by a ruling class of dragons, bigger than elephants, who were able to breathe fire and fly anywhere.
Initial contact would likely be less than pacific or communicative.
The juveniles are especially rancorous. They are still trying to prove themselves, and they require protein for their growth.