All of the above. If you look on matlabs page a little further down, it becomes apparent that matlab initializes a canvas (the screen), then looks for each pixel what is directly behind that screen. This gets rid of perspective. When you set the camera angle to 45 degrees down and 45 degrees left/right, you will get an implicit isometric projection. So really the "projection" just depends on your camera angle.
Sidenote: if you would want to keep a 3d perspective, you would need to draw the ray from the camera origin to the position on the canvas. That gives the ray the direction it needs to create perspective.