The first thing I notice about that chart is how many turning points are listed. For goodness sakes, he's bound to hit something, especially if he is not saying whether or not he thinks it will be a high or low. The only way he could be wrong was if the market went up every single day or down every single day. As long as there are even minor reactions, he will be able to claim some accuracy. He could possibly be credited with something if that market has a long sharp defined trend between the dates of Feb 17 and July 29, as is implied by the chart. If his bold dates are of higher importance, that also could be beneficial. I'm not trying to rain on the guy (I don't know a thing about him). It is a somewhat different thing to measure TIME AND PRICE together, to identify prices in time that define the trend (points that will not be broken). At these turning points, price will balance with time to confirm the turn.
As for your question to explain why he chose these dates, this is a good question. Every market (or sector) resonates with the individual cycles differently. If this were not the case, every market would be identical, and every market chart would have the same dates for turning points. The grains (which i study exclusively) are synchronized more closely with certain cycles than I'm sure stocks do. All this to say that I don't know why he has chosen the dates that he has.
I understand the desire to chart the projected turning points, and you are very good at putting the material in a visible form for the reader. I just have to be careful with the things I say on this site. I have had many instances where someone intentionally twists any information I post.