?...and there are at least two ways that it can be gamed by the same ethically bankrupt people that were gaming the system as abled park guests that forced the change in the first place.
I don't recall that Disney ever claimed that DAS is foolproof. The biggest abusers of the old GAC were, sadly, family members of legitimate card holders. In a typical scenario a family would get a GAC for Grandpa, and the grand kids would then use it as an instant Fast Pass for the rest of the day while running through the parks from ride to ride without Grandpa. That abuse has been stopped.
And it is now much more difficult for an able-bodied individual to simply lie about a hidden non-mobility disability. The Guest Relations CMs are asking hard questions and no longer have to give in to apparent falsehoods.
As for the news reports of disabled persons hiring themselves out to get a GAC, I suspect that such occurrences were extremely rare, if they happened at all.
Finally, is it likely that a CM will know the initials of the others working at the attraction that day? Yes, it is. I'm a CM at Animal Kingdom, and I always know who I am working with. There are also backup measures ready to be put in place, such as colored inks and code words that can be used instead of initials.
Cheaters beware. Expulsion from the parks is now a very real possibility.