This is very interesting and does certainly support tornadic winds being stronger than the EF scale predicts, but one thing worth mentioning is that it appears that this data was taken on the right side of the tornado, so the forward translational speed is added to the actual winds too. I'm not sure how fast El Reno 2011 moving, but I'm guessing it was pretty quick based on some of the videos I have seen of the monster. This point also doesn't really discredit the storm's power in any way, as I am a firm believer in a faster tornado's forward velocity significantly contributing in how intense damage can appear, so I don't believe it should be used as a critique on the intensity of the storm either.
Also, I'm a bit more uncertain about this point but I'll give it a stab anyways - it appears that this windspeed measurement is located near the outer edge of the circulation. Wouldn't the winds here have a strongly horizontal component to them, and thus be more comparable to a gust from a strong hurricane? That might be why that, despite the strength of these winds, they only produced "EF0" damage.