Man's online buying habits trace German customs to his arms cache

Is he... an extremist?

doesnt have a muslim sounding name.. so as per PC handbook.. he is a lone wolf. Like the ginger who was arrested. Though thats just wrong. Who even arrests a Ginger?
This is confusing.

Did the Authorities figure out he was buying illegal stuff because A) his illegal stuff or the paperwork get spotted by customs, or B) the Authorities were pro-actively surveilling his online activities?