Actually we asked.
They are not interested in any technology that would get them into space. They do not want warp drives, geller fields, even rockets. They don't care. I mean they'd have the ability to make them, but according to them they wouldn't.
They are behaving within the normal bounds we already established that being unless its to fight chaos or possibly necrons they will fight to keep themselves on the planet and react angrily to attempts to take them off it.
This handily removes the main problem of tech spreading, namely that getting to another polity to trade with is very very difficult on Avernus unless you can cut out the problem of everything in between being out for blood. Flight doesn't cut it, you need to go out of atmosphere to travel that distance safely. Another thing that is in the way of potential tech spreading is that Avernite species seem rather adverse to their stuff getting into other native people's hands, i.e. the Sirens and their runes. They're fine trading them to us and even trading them to other humans, but they were much less happy with trading them to other peoples.
It also removes the problem of colonisation, they seem to really not give a shit and that seems unlikely to change.
However to double check
@Durin
1. Are the Nyne in anyway interested in leaving Avernus for any reason beyond fighting chaos and potentially necrons?
2. Do they expect this to change if they received the ability to do so (go into space) without us being needed to do so?
3. What would they do if we attempted to force them to leave.
4. Do they even want any techs that would allow them to leave the planet such as warp drives, space based geller fields ect.
5. Do they have any restrictions on trading their alkhestry either to species off Avernus or other peoples