The point of the experiment was to illustrate that all of this talk of "proper perspective" as expressed as a single lens focal length, is a complete ruse.
To clarify a bit further, perspective is entirely a question of camera-to-subject distance. Different focal lengths obviously provide a different angle of view. If you fill the frame with a same-sized subject with two lenses of different focal lengths, simple trigonometry tells us that that means a different camera-to-subject distance and therefore a different perspective.
Depth of field and background blur is a function of aperture -- but not the f/number; rather, the actual physical size of the aperture. So, do the actual division and you'll discover that a 50mm f/2 has a 50/2 = 25mm physical aperture, and a 200mm f/8 has a 200/8 = also a 25mm physical aperture. So, if you stand in the same place and take a shot with a 50 f/2 and 200 f/8 and crop the 50 to the same angle of view as the 200, you get, for the most part, an identical image.
Obviously, 200/2 = 100, so a 200 f/2 image has much shallower depth of field than a 50 f/2. Add in perspective changes and the end result is that a head-and-shoulders shot from a 200 f/2 has a much shallower depth of field, a much more compressed perspective, and much more background separation than a head-and-shoulders shot from a 50 f/2 -- assuming, of course, the 200 is shot from four times the distance as the 50 and no cropping.
There'll be a similar difference between a 135 f/2 and a 100 f/2.8, but nowhere near as dramatic. Indeed, it'll be just about the same difference as between 135 f/2 and 135 f/3.5. Different? Yes. Dramatically different? No.