i am THAT guy
See it has a reason, an agreement won't protect you from a lawsuit, ok everybody agrees when you say "it's not for profit - it's no problem".
Fortunately i haven't run in such a lawsuit (yet), besides can you strip a naked man?
An experience i made with "Pioneer" and my models, i had the agreement of "Frontier.dev" to use the original Frontier art.
But i had to agree to the devs of Pioneer, that if a lawyer would start a lawsuit this spoken out agreement would worth a shit.
They would have to act and we would be fined (things are complicated today - aren't they? when a word between two men counts nothing anymore).
Thus i agreed that all my Frontier ships had to be removed (strangewisely all was removed not only the Frontier ships).
I no longer mind about that.
But that's why i'm maybe a liitle to cautious.
and you see it's not so much the management which matters, it matters if a sleek lawyer starts a lawsuit,
means i could have had the personal agreement of David Braben, and it would still worth a shit.
For your developements you won't have to mind i guess, they will never be this close as my models was
close? unit by unit they was the same, i blatantly copied the geometry from the original game, since our previous modelling system and frontiers internal way to draw the models was similar, draw bezier, draw flat, etc.
I learned in this way a lot about 3D models of which i guess by far not everybody who creates them knows about, today you work with a CAD and not with "draw bezier",
but the rules how they work are stil the same and the errors you can run into are still the same as 25 years ago.
if it was about me i would say "do what you like with it", but it isn't that easy.