Well, I can imagine that guitarist playing blues, but that tune is so different from the usual dull melodic structure of blues pieces that I would find it hard to call it blues or bluesy.
It's funny though... some years ago I was a bit taken aback to see that Jimmy Webb (who of course wrote that song) was to be one of the featured artists at a Blues and Roots festival. He may have written one or two songs that have a bluesy feel, but I would never have thought of him as a blues singer or songwriter. I seriously considered going to see him, but decided I did not want to sit through a day-long blues festival just to hear Jimmy Webb for 20 minutes, especially as it would have involved travelling from Sydney to northern NSW.
I'd be more likely to apply the label "progressive" to Webb - though he was doing it before the term "progressive rock" was invented.