Generating normal map blue channel

[pepperoni505]

I've seen #53, and I am currently trying to convert a normal map which has an empty blue channel (https://www.dropbox.com/s/o69kon4f0s12ifm/normalmap.DDS?dl=0), using this command texconv.exe -y -o C:\Users\pepperoni505\Downloads\ -f rgba -ft png -reconstructz C:\Users\pepperoni505\Downloads\normalmap.DDS, which generates the following image:
The issue is that the blue channel is too "grey", and it should look like this.

Is there a way to achieve that?