Cancelling cancels inertia? Are you sure about that? A craft if so arranged that it is an internal inertial system to itself will be ‘immune’ to gravity since gravity and inertia are so closely related.
This of it this way.... To the people inside the craft they feel like they are standing still. Space around them is moving.
They don’t feel any inertia because in their inertial reference frame they are not moving.