It is possible to swing between a BWO BHS and connect the skills, but of course it is preferable to connect without an arm swing. However, I typically see more of a circling arm swing in the series that are connected with a swing. With the up-down sort of swing, most girls drop their chests forward, which breaks the continuous movement backwards.
I also want to point out that the deduction for not connecting an element to the dismount is nowhere near as large as failing to connect an acro series that starts and finishes on the beam (BWO BHS, etc.). An acro series is a .5 requirement; an element into the dismount is not. The worst that can happen for a cartwheel back tuck is that you can get hit with a rhythm deduction in the connection or the skills are considered unconnected.