So yes, it imposed abortion on half the country. I'll also point out it imposed, through the trimester framework, when life begins (ie. when a baby is viable to survive outside of the womb and thus have an interest in life).
The imposition of the idea of when life begins on the entire country is exactly what you just argued against.
So in this case, Roe imposed not just abortion on the states that didn't want it, it also imposed an idea of when life actually began.
Or do you not know what imposed means?
A state is a fictional political entity. It exists to serve its citizens. The moment the rights of a state to be an independent political entity requires violation of an individuals bodily autonomy, its rights can take a hike.