Sikh first to understand, then to be understood...

That's not an especially helpful statement - he COULD have been a member of a race hate group, he could also have been a world class tap dancer. Or both.

Being that he's dead, you can't really ask him about his political beliefs; he may have tattoos, but you say that he's a "former soldier" and a "skinhead".

They cut your hair short in the army and many vets keep up the habit in civilian life.

So all of this is just guessing and police pre-emptively covering their ass.

There are any number of reasons why he may have chosen to shoot up a Sikh temple, if indeed he DID choose to shoot up a Sikh temple - perhaps they owed him money..?