Claim that Wilber does not consider himself Buddhist 

According to Ken Wilber, One Taste (1998, Shambhala), p. 351., he says “I am a longtime
practicing Buddhist, and many of the key ideas in my approach are Buddhist or Buddhist
inspired. First and foremost, Nagarjuna and Madhyamika; pure Emptiness and primordial Purity
is the ‘central philosophy’ of my approach as well. Also Yogachara, Hua Yen, a great deal of
Dzogchen and Mahamudra, and yes, the fundamentals of Abhidharma…. Again, I’m trying to
take the best from each of these traditions and bring them together in what I hope is a fruitful
fashion." 

Has anybody verified the 2003 source given in the article where he purportedly does not call himself a Buddhist?

With two conflicting sources, it might be better to remove that sentence. However, you could also argue that the more recent citation is valid since he is a dynamic and changing individual.