Andy, you have to exercise one of my pet peeves this early in the morning? Don't drill "stop holes." Doesn't usually stop anything. Reduces the strength of the frame. Encourages crack growth. Nobody in aviation would ever drill stop holes and not fix the underlying condition. The end of the crack is actually under compression, which keeps the crack from growing as fast. Drilling that out removes that. It's one of the factors that make ductile metals so useful. There is nothing driving this crack to grow, so leaving it alone is a good idea. Maybe paint over it.

Next someone will bring up shimmy and I'll have to take a timeout.