I am not sure the effect your looking at is purely, or even primarily, color treatment. Some of the photos you have linked are black and white, some are color. Regarding the color images, they all appear to be largely, but not entirely, desaturated. They also appear to be largely white balanced, with only slight shifts towards the cooler or warmer temperatures.

Overall, across all of the images, I think the key factor is lowish contrast and clipped or nearly-clipped highlights. Larger areas of bright backgrounds are allowed to encroach upon the foreground of many of the photos. Bright background highlights, usually the sun, are often used to intentionally create soft flare and create a localized contrast reduction. I have also always liked Sean Flanigan's work (ever since I first encountered him), and his style has always kind of felt "journalistic" to me, with a touch of retro. I guess thats the name I would give his style, "retro journalistic", which is somewhat unique, and which does indeed include real tilt/shift photos taken with a TS lens.