I'm inclined to write the original post from Vincent off as rumour mongering without anything more substantial. The failure to deliver a UT3 Linux client has irritated quite a few people, and I can certainly see that creating motive to smear their name.
I can also remember earlier accounts had the issue as being a dispute with a third party over middleware licensing. This is not consistent with the unsubstantiated rumour.
I am not the guy that likes to spread rumors, but I also don't have any evidence to prove it. You're just going to have to believe me or get Icculus drunk as hell :')