I think government regulation probably only advanced the inevitable. Synthetic substitutes were developed for performance (temperature tolerance and service life). It was likely only a matter of time until said substitutes made their way back into older specifications for oil due to natural economic incentives.
Perhaps there would still be some niche whaling if not for the ban, but it would be for a niche use, not because literally every automatic transmission in the country needs a cup of the stuff.
Often when there is government regulations it is because those regulated approve. Not always, but often. Oil refineries are attacked in the press by government, but when they want a permit to do something it is always quietly granted.
There is no "only" in advancing the inevitable. A century may be a blip on the geological timescale but it makes an enourmous difference for civilization.
A century from now, global warming will be "solved", one way or another. The open question is what civilization looks like.
There is stil some niche whaling. It's all done for meat, but if there was any industrial value for some parts of the whale, I imagine that would be extracted and sold. I don't think there's anything like that.
> Perhaps there would still be some niche whaling if not for the ban
There is still whaling. Iceland, Japan, Norway, North American indigenous peoples and the Danish dependencies of the Faroe Islands and Greenland continue to hunt in the 21st century.
Worse, Iceland, Japan and Norway still engage in and supporting commercial hunting.
