Mike,
Tom and I have known for a while now that Wilson was credited with working on 2 holes on the South Course. We also speculated that Flynn was likely involved in some capacity at that point. Until Joe came up with his compilation of articles, we didn't know which 2 holes they were. Strouse's contributions and references to other work were completely new to us. I agree with you that Flynn was involved in some capacity at that point. He and Wilson became very close and worked together on many refinements at Merion East and the development of Merion West. There is some archival evidence that Wilson visited Flynn at Kittansett, he and Flynn did redesign work at North Hills and Wilson worked with Flynn at Marble Hall (now Green Valley CC) at the time of his death. It is possible that Flynn may have helped out at Phoenixville CC (if Wilson in fact designed the course) and Wilson may have contributed at Doylestown and CC Harrisburg. Wilson and Flynn had the added value of being very far ahead of the agronomy learning curve at that time and these skills in redesigning courses would come in very handy.
Willie Park, Jr. was much more well-known than Flynn during the design and construction of the North Course. Not only that, but he came from Scotland and was an Open champion. Although many renovations were made to the East Course at Merion, Flynn's portfolio was still pretty small (it never amounted to more than 45 or so courses designed and built). Except for Lancaster CC and Cherry Hills CC, most of his best courses would not come about for a few more years. If it was Willie Park, Jr. that designed the North Course at Philmont (and it seems that way at this point), they chose very well.