I use this strain frequently and have noticed similar results. At the 2-week mark, the krausen is still substantial. I let mine in primary for 3 weeks. In that 3rd week, the krausen settles out pretty well. Scientifically, I'm sure the yeast has it's role (flocculation = medium, sedimentation characteristics, etc.), but it probably also has to do with proteins, hop oils, etc. in the beer itself.
Give it another week, maybe cold crash it or keep it at a cool temp... it will settle out.