moving with space is only supported for draging out a rectangular mask or a rectangular show/hide stroke.
He did not mean holding either ctrl (mask) which invokes maskPen brush or ctrl+shift which invokes selectRect brush for showing/hiding portions of you mesh, when starting the stroke from the outside of the object.
it is not the actual sculpting brush that you can move by pressing space.
He wanted to move the already dragged out (scaled and aimed) stroke of the actual sculptingBrush (with stroke type: dragRect) to adjust the positional placement, which would be a really nice addition to that dragRect stroke type, but unfortunatelly does not work in that case.
Thanks for putting in the effort for the zAdjustor plugin :).
I will try it.