Author explains why on the page. Search for "Basically, that is a reason why I’m not open-sourcing the code yet."
I read that. My point stands. "It uses horrible hacks" isn't a valid reason. Actually, I don't think there is a valid reason why not to release code that does something interesting and you want to show people.
As it said, it works now only with simple code. Even for primesieve example I had to modify code, unroll loop and so on. The approach itself is limited, though it was enough for my task.
I'll try another option (with Vyukov's tracer), which will be, hopefully, the right way to go. Will see.