Read the article. This office was run by the state GOP, not McCain. Both major parties (and some of the others as well) often rent empty storefronts to use as campaign offices. These are short term leases of whatever infrastructure happens to be in place. It would be unrealistic to install alarm systems or window reinformcement for what's probably a 3 month lease.

Campiagn offices are always very well marked and only 1 item was stolen. A random theft? I doubt it.