You do (finally) have a reasonable point that people could forward deploy shields offensively. Listening posts seem totally unimportant to me (thats not how mortius found you by the way). However, out of curiosity how would your proposed scenario be different from someone colonizing multiple systems and forcing you to spend a week besieging each of those instead (assuming you feel the need to prevent listening posts from existing)?
Also, yes I think players should have to actually build stuff to defend themselves, not just be imbued with the magical property of taking a week to besiege despite potentially being stick flinging barbarians.
Also, yes I think players should have to actually build stuff to defend themselves, not just be imbued with the magical property of taking a week to besiege despite potentially being stick flinging barbarians.