When I bought my Boxster it only had a wind blocker in the driver's side roll bar hoop. The mystery of what happened to the one on the passenger side was solved when I discovered it's mangled remains at the bottom of the compartment that the convertible top folds into. The used replacement I bought to replace it had broken tabs, much like yours. I was able to graft tabs from the broken original onto the e-Bay replacement using epoxy. Not sure if it's obvious in the photo, but I reinforced the join with a second layer of plastic that was also obtained from the original. I did this repair about ten years ago and it's still going strong.
Do let us know if you're able to repair yours. -dj