You see, the cool thing is that BPM is typically project funded. This means that within a given enterprise, you have a considerable lot of BPM projects, whether it be supply chain logistics, order to cash, some cool RFID project, call center, there are hundreds of processes that can be optimized. Optimizing a process leads to clear ROI and you can justify spending millions of dollars for the resulting improvement to the business.
So if you can link your SOA infrastructure to one of these projects, you can get components like Registry Repository and runtime policy mediation systems that have Enterprise wide implications. This can create significant value over time and across projects.
Whatever you think the relationship between BPM and SOA really is, this is excellent advice.