That doesn't make sense. It says they're refusing to allow Tesla to pick up the license plates as well. And in any case, is a picket line a legally protected entity now?
Postnord should not refuse to let Tesla collect the plates that Postnord has. That would be theft
I'm using the word "picket line" informally to describe a strike / labor action, which I would guess is a legally protected and regulated thing in Sweden, as indeed in the US.