I don't think they are "true". The Id cards are genuine, what the SC community manager tried to say in his twitter was that these were some kind of "generic cards", not "id cards". IOW, they didn't prove these guys worked there.
But the problem is in the details. Let's not forget that these cards are specific. It's not that they alone prove they worked there, it proves they had access to cards built in the exact same manner. And they didn't just show the cards. They also showed pay stubs (?). And, apparently, they all looked the same. And there was also corroboration (for at least a few) by checking their LinkedIn accounts.
I see two possibilities of fakery here: either The Escapist is lying and fabricating everything (total fantasy fiction yey!), or all of these guys were highly coordinating between themselves, getting equal cards for each one, printing similar payment papers, forging LinkedIn accounts, etc.
I find both possibilities unlikely. I find the possibility that we are just witnessing disgruntled employees ranting about their last job some orders of magnitude more likely. It would also be consistent with the CIG saying "Well, they are absolutely exagerating everything and it doesn't surprises us, for they are disgruntled", or smth to that effect. But this simpler analysis isn't useful to sue the Escapist. One could speculate that these claims of forgery were "planted" in social media so they can porsue "investigations" of defamation, etc. A lot harder to do if it's just "disgruntled people", although I don't believe any of these reactions were really "coordinated", it's just all happening with too much rage and in real time.