Maybe, maybe not (and I think, after looking at some of the facts and using some common sense, not)
I seem to recall that the timing was made on the ground using clocks that were synchronised before the experiment started, in addition to GPS clocks - the results would not be the same for each type of clock if this was a simply GPS-related mistake.
Also, the GPS satellite that this guy is talking about is not the only one in the sky - there are several used by every receiver at many different angles, not just 55 degrees to the equator, and at different times (approach and departure). Again, those different GPSs and times would give different results if this kind of thing wasn't taken into account.
There's no way to tell at this point whether he's right or wrong about this until his paper has been properly peer-reviewed, but expect some of the press to jump on this as the answer anyway.
