One thing he argues is that the Umayyads were the Petra 'traditionalists', and the Abassids the Mecca 'reformers' who later won the day and created the new Qibla.
The Umayyad dynasty continued in Spain though and by this point orchestrating an empire wide realignment along with places outside the empire would be somewhat challenging. Mid 8th C seems a bit too late.
His theory about all early mosques pointing to Petra presupposes a high degree of accuracy in alignment, which I'm not sure existed at the time. Would be interesting to see further research though.
There is also a story about a mosque in Samarkand where Hanafis prayed west and Shafi'is prayed south before compromising on Southwest (presumably 9th C). This might suggest that directional precision was not expected to a high degree, as long as you were praying in the general direction.
The Quran is a theologically sophisticated text that presupposes a high degree of knowledge of late antique religious discourse which does seem better suited to a less parochial environment than Mecca, and one that had strong Syriac influences. The script of the Quran also suits a North Arabian context better according to
this, as well as some of the verses in the text itself.
On the other hand there is also early 'Islamic' graffiti in Central Arabia. The most intricate features inside the Dome of the Rock seem to be directed towards Mecca also.
Northern Arabian tribes had been serving in the imperial forces of both Rome and Persia for centuries (possibly even forming the majority of Roman forces by the time of the conquests). Islamic tradition has early Muslims fleeing to Christian Ethiopia, which was a Roman ally (possibly fleeing from Persian aligned Jewish Arabs??).
This "Roman connection" could provide a conduit for Syriac religious affairs to reach further into Arabia than might be expected I suppose.
Without more substantial evidence I'd still be inclined to view Jerusalem as the original Qibla, especially seeing as Muhammad seems to have been most aligned with Moses in scripture. It seems most likely that changes in the Qibla would have occurred prior to the 1st Fitnah as it would encounter greater logistical difficulties the longer it took after that.
The 'reification' of Islamic identity seems to have occurred under abd al-Malik. Not that he invented it, but the historical record pre/post Malik is markedly different. Again making a Qibla change after this point less likely.
Like most things on this issue, some evidence can be seen to point in one way, while other evidence seems to point in another.