5D MKII ISO 4000 missing?

I think you missed the point the previous poster was trying to make.

The video community surrounding the 5D mkII quickly learned that certain ISOs were better than others (cleaner).

The lowest noise was to be had in:

160, 320, 640, 1250

also good:

100, 200, 400, 800, (1600)

1250 gives lower noise than 800. It's counter intuitive, but still a fact.

The reason for this is that the only true ISOs are 100, 200, 400... and so on.

160 is actually exposed at 200 and then "pulled back" in camera. 250 would be exposed at 200 and "pushed". The pushed ISOs tend to give more noise:

125, 250, 500, 1000, 4000...

Your ISO of choice is a push ISO and the question was if this was a deliberate choice or not.

All this said, I think the push/pull effects are especially important up to and including 1600. After that I think I remember a more intuitive noise curve, where higher ISOs are noisier than lower, regardless of push/pull.