I don't use Jeff's method but the dough at the end of the kneading process should be smooth and elastic. I estimate your hydration to be around 63%, so there should be enough water to get a finished dough ball with the right qualities and a finished crust with a fairly soft crumb. You can get a tough and chewy crust if you overknead the dough, but my recollection is that Jeff's mixing/kneading protocol is not that hard on dough. A longer fermentation time might allow for the gluten to be softened further, but in my experience I have not seen a marked reduction in the chewiness of the finished crust.
Usually, if the objective is to reduce the degree of chewiness, the first step taken is to use a weaker flour. You could try adding some all-purpose flour to the KABF to lower the protein content of the blend to something lower than the protein content of the KABF, or you could try using a weaker bread flour, such as the General Mills Better for Bread flour (also sometimes called Harvest King flour). I personally wouldn't use all-purpose flour alone but that would produce a softer and less chewy crust.
Another possibility is to add some oil to the dough. That will help retain some of the moisture in the dough and produce a softer crust and crumb. If you go this route, I would consider using about 2% of the weight of the formula flour. In your case, that would be about one tablespoon.
If you reduce the total bake time, that will usually help produce a softer, less chewy crust and crumb because the dough doesn't dry out as fast. To do this, you would usually use a high bake temperature and a short bake time. That regimen has to be balanced against the need to have all of the toppings properly cooked by the time you remove the pizza from the oven and without having a gummy dough or pasty crust because of underbaking.
A final possibility that comes to mind is to proof the dough skin for about a half hour before dressing and baking to let the skin rise and become more like an insulator and yield a more open and airy crumb in the finished crust.
You may have to conduct a few experiments in your future efforts to see which, if any, of the above recommendations produce the results you are looking for. If you find a solution, I hope you will let us know what worked.