Theoretically, Kevin, you're right. But there are two compelling reasons to try to include the "official" DD EX that I think are the true reason Outlaw held out for DD EX in the 950.

1) I'm going to assume that Dolby and THX are fairly protective of their decoding algorithm, and likely to sue anybody duplicating it outright. Therefore, the 1050's "Surround 6.1" and the 950's original 6.1/7.1 decoding had to be done based on the fact that Dolby and THX were using a matrixing scheme similar to the familiar Pro-Logic -- starting from the same origin and Dolby and try to come up with your own (mostly) compatible approach. For those two reasons (secrecy of specific algorithm and patent protection for Dolby and THX), Outlaw's older schemes of 6.1/7.1 would seem to have to be different.

2) While THX-EX remained limited to expensive THX-licensed gear (and Outlaw has been fairly clear over the years that they have no interest in adding the expense of THX certification to their products), Dolby Digital EX will quickly find it's way into a lot of upcoming products. Including it in the 950 will help keep it competitive with next-year's gear. Sure, the old decoding might have been able to compete in terms of performance, but it will be very valuable to be able to have true DD-EX rather than an "equal to" (which can easily be construed as "cheap knock-off" in some consumers' eyes).

I personally don't think the Outlaws used the announcement of DD-EX as an excuse to cover up problem. I think they made a good (if extremely difficult and inevitably hotly-debated) decision to try to include it. I can guarantee (speaking as a design engineer of a very different sort) that plenty of their designers heard the DD-EX announcement and had two reactions: first excitement ("Cool! We've been waiting for that for 3 years!"), and then horror ("Oh, sh*t... Are we going to have to try to cram that into the 950? We just finished it!").