If my memory serves me correctly Pat Crockett is the guy's name that plays ukulele in Taj's band, on The New Hula Blues and the like... Taj lived on Kauai for a number of years. I am sure he has picked up an ukulele from time to time. That's about all the light I can shed on the picture.
I saw Taj at the Blues and Brews festival in Telluride Colorado in '01 (before I had a reason to notice ukuleles), and I am pretty sure he played one on a few tunes. He was really great, but mostly at that point I was trying to stay warm until James Brown came on!
I saw Taj last night. Great show and he was wielding an 8 string Kala in addition to a resonator guitar (his work horse) and a 5 string banjo. He played them all quite well.