I think shutter speed is more important. Your subject is moving and possible fast if breaching. VR wont help with that. There are also other sources of motion. The boat may be under power or drifting. And the boat may be rocking on the swell or waves. VR might help a bit with some of that, but I suspect often it may not be enough on its own.When photographing whales, how crucial is stabilization in capturing clear shots, especially with the varying distances they might be from the boat?
I tend to leave my cameras VR on in sport mode for my Z9/Z8. At higher shutter speeds, you may not need it to keep the photo sharp, but helping to stabilize the viewfinder can still be helpful.