One of the new PSP's were really hard to hack, and was virtually unhackable for a few months, but it was cracked, though with a runabout fashion.
It is also good to remember players are typically "Not ordinary people" but are "exceptional people." Still understandable that not just any player could hack into it, but instead a plot duex ex that allows it for specific events.
Virtually, one could only be unhackable if the version of it changed, or patched, every day. Though I'm no hacker, I'd assume a new version means a new change in the programming code and therefore, original hacks cease to work.
Additionally, this is assuming PANTHEON is only accessible by one browser (being an Empire, it probably is) and therefore would need to be checked as well.
One can't really hack the internet itself, only the computers that connect to it right? It's like trying to hack reality if that was the case (Aka, sorcery).