O.K.
I think I understand.
You are asking TheFGPhilippinoPilot if he is O.K with
you pushing his work to TerraSync (the 3d models), granted they are GPL?
that's a fair question, actually.
The only objection is that by you pushing yourself, can you give credit to the author? or are you pushing this content as "made by you?". The reason why this could be controversial is that even you can use GPL material by redistributing, the License does require "atrribution"
Other than that, I think, it is fair for you to ask to the FGPhilippinoPilot if he would accept your reuse of the material he posted. If you asked me, given that the material is GPL, his answer should be: "Feel free to use it as you seem fit, provided you respect the GPL license terms, and keep all copyright notices and disclaimers of the lack of a warranty, as well as proper authorship attribution"....
And from there, you off course could use that material as you see fit