Speed of light during acceleration

[Ibix]

I no longer think the last part is correct where I said:

I agree. I think you edited your post - it was shorter when I "like"d it. There are no objects following the lines of constant Rindler time, since those are spacelike. In fact, they are not lines except on the 1+1 dimensional drawing - they are 3d planes in a full 3+1 dimensional case, and are a Rindler observer's notion of "all of space, now" (which goes wrong where they cross at the Rindler horizon).