This is what happens when companies get aquired. I'm working at HP now, which used to be Compaq, which used to be Tandem. When Compaq aquired Tandem, they also acquired the right the claim that their machines ran all the major stock exchanges. When HP acquired Compaq, they started making the same claim.
However, the difference between that and what RedHat seems to be doing is that in our case, though the "owner" changed, the hardware, software and people didn't. What RedHat acquired isn't what Sloan uses. What Sloan uses is what ArsDigita threw away to start over and create what RedHat bought.
If you wanted to give RedHat the benefit of the doubt, you could assume that they meant to say that ACS is really about the datamodel and not whether or not it uses TCL or Java, but I'd like to hear that directly from the horse's mouth.