Speculation: I believe it is one of the Archaic stemmed knife forms that broke late in manufacture. In the third of the first series of pictures, looking at in cross section, he is flat on one face, and domed on the other. To thin the domed side he would need to trim material from the edges to move the edge under the center line of the domed side. This would have wasted width which in a knife you want to keep for re-sharpening. Instead he tried to thin that area with a more risky strategy of coming up from the base. The fourth picture in the second series gives another hint at why he did this. See that seam running perpendicular to the left edge? He couldn't flake across that and instead ran the flute like flake parallel to it. Looks like that flake was either too aggressive, mis-struck, or ran into a hidden defect and the biface broke. I believe the two flakes on the other side are just fairly aggressive basal thinning flakes which are somewhat common on large stemmed points. For example, flute like flakes in the stems of Savannah River or Perdernales type points are not all that uncommon. If it happened like this, though, it should have been found at the manufacturing site, so close to the stone source.
