It sounds like a reasonable idea to me. It might explain why it's so sparse in areas outside the traditional Corded Ware zone (excepting some later incidences). I recall that a number of people think it was quite late on the scene in the western half of Europe. Would 700BC for the Rhine be considered 'late' in comparison to P312?
It seems to be more continental though, and seems late in both western Europe and Scandinavia, which is interesting. Maybe it was 'picked up' by Corded Ware or something, and formed a western extremity?
700 BC is relatively late, but that is about the time that Germanic-speaking peoples arrived in the area of the Lower Rhine.