Once a point is admitted as a boundary or a location within a line or body, one must ask what kind of dependence it has on that host. If it is merely a limit or endpoint, it has not been shown to be a separately subsisting bodily atom.
The discussion distinguishes ways of speaking about something being “in” another. Such a relationship need not mean that both are constituent physical particles of the same kind.
Thus the existence of a limit cannot simply be converted into proof of an independent indivisible substance, including in the sphere argument.