The Bloomberg article is about fresh water spills, with the study done by Canadian government using product provided by oil industry and tested in lab conditions.  The reality is that dilbit adheres to materials in the water like sand and silt which means that the window to recover any is in the first 48 hours under ideal weather conditions.  Beyond 48 hours most will sink.  

http://canadians.org/blog/national-academy-science-report-points-dangers-bitumen-spills