It might be “hard coded” from PL’s point of view but 5200°K is not the normally accepted temperature for daylight.
If a camera has been set to automatic WB, the image will already have been adjusted, in camera, to what the camera thinks daylight should look like. What that temperature is will depend on the camera manufacturer. Then PL has its own idea of what daylight is.
According to this chart, daylight can be anything between that produced by a low sun (5000°K) and that produced by the sun being directly overhead (5500 - 6000°K). The generally accepted definition of daylight for photographic colour integrity has been 5600°K for many decades.
My guess is that DxO, along with some camera manufacturers, have chosen 5200°K because it produces a slightly warm rendering, which psychologically makes people feel “happier”.
The truth is, you are free to choose whatever temperature suits the mood you wish to convey in any particular image.
But to return to @zkarj 's original subject, if the “as shot” automatic WB temperature is near enough to what DxO calls daylight, then you won’t see any obvious change. The difference between 5200 and 5270 isn’t worth worrying about.