Peculiar. I could not tell if the nose is high or low form the picture, but looking at the F4 board profile, it is clear that the tracks are indeed angled that the nose would be higher. In the right image, you've got the board angled more, so the apparent wind would push the nose down more. To compensate, moving the back foot back into a wider stance makes sense.

What would that have to do with the angle change, though? Here's a theory: when dropping the rail to re-direct the lift so that you can go faster, the rail gets closer to the water. Touching chop or waves with the forward section of the rail could cause problems. increasing the fuselage angle to raise the board nose would reduce this problems. There's been plenty of posts about shimming the mast plate to also increase the angle; IIRC, one argument was that this also makes touch down recovery easier. The F4 guys seem to be into racing and going fast, so maybe there's something to this theory.

I think this picture explains well how it is.
And after discovering this, I have been googling a lot about rake/rocker. And I read many places that guys on fast foils have quite a lot of rake/rocker, to have 3-5 degree angle difference between the deck and the fuselage.