I guess there are more than a single way to put that dang spring in place!

 

The service manual states to "apply a thin coat of molybdenum disulfide grease to the new cam part surfaces" when installing a new camshaft. So, ignoring Kawasaki's lack of expertise in camshafts (or at least the KACR portion, anyway ), it seems like using a dab of moly grease to hold the oil filter spring in place is an Ok idea.

Coupled with tremor38's comment that some oils use grease as an additive, it actually sounds like a good idea!