Yeah, I've seen this, too. I think there are at least two ways to achieving a good tremolo; (1) keeping the hand in the normal/default position and extending "i" to compensate for the angle of the MCP's, or (2) turn the entire hand a little bit to allow "i" to reach the string without extending as is shown above, and not changing it's normal motion to the string. I would think that there is a middle ground between these two approaches as well.
I personally like to turn my entire hand (not as much as Segovia). I find this to be more consistent, but I played the other way for a while and it worked ok, just not as effortless. I also find that I like my knuckles (MCP's) more above the string that I am "tremoloing". I also use a shorter nail.
For what it's worth, your mileage may vary.