I only offered one source, and the research it quotes suggests no such thing, so your comment seems a bit odd. The closest it comes to saying what you suggest, is not very close at all:

But a spokesman for the SWOV acknowledged that the protective head wear might be a hard sell in the Netherlands. ‘Helmets aren’t often worn in the Netherlands and we are aware of the arguments [that cycling could decrease if they were obligatory],’ he said.

I'm not invested in what happens in the Netherlands at all, but I wonder if a lot of people are just taking "the downtick in injuries would be overshadowed by the reduction in biking" for granted.