I am almost certain that Blizz has access to all the tools that we ourselves have access too to spoof or hide IP addresses, as well as a number of other ways to mask their identity so the HB/GB team may have a hard time isolating them from the rest of the masses, but then again I don't think these guys are quite human(perhaps...roBOTs?...yeah I know...sorry just had to), so they may be aware of them, but they likely won't and shouldn't tell us if they do.
I mean I think we all know that not every Blizzard employee sits at a desk in Irvine, California. I applied for a few security related jobs for Blizzard in Irvine, CA a few years ago but turned it down as the economy wasn't ideal for uprooting my family from the east coast of the US to the west coast...they wouldn't even offer relocation assistance!!! bastards, LOL. Their loss, but I love my current job of 7 years... my 'white hat' fits nicely

Anywho, the jobs at Blizz were pretty cutting edge IT security, red team, vulnerability testing, and all that stuff. So if they are concerned about what comes in.. you can be sure they control what we see from them as well.