I didn't have a chance to read your article until today, so I hope you're still following this thread.
Something is not quite right with your timeline for WDW's keel boats. My one and only visit there (to date) was back in September of 2000. On one of the days we were in the MK, the keel boats were definitely operating. I vividly remember this because I never got to ride them at Disneyland--my timing always seemed to be off, and they were never operating there during my annual trips (it became a running joke!). So, I was very excited to finally be able to circle the river in one. We eagerly boarded and took our seats, and then--a distant thunderclap. Since we hadn't left the dock yet, we were immediately ordered off the boat! The operator told us all water craft had to shut down at the first sign of a thunderstorm (makes sense for safety, but I was still very upset). It rained during the remainder of our time in WDW, and I never saw them operating again. I guess the universe didn't want me to ever ride a keel boat!
Anyway, perhaps WDW just ran their keel boats seasonally after 1997, just like Disneyland.