Randomly wiring a neural net doesn't remove preconceptions, it just makes it that you don't know them. Similarly, closing your eyes doesn't make a room empty, it just makes it that you can't see what's there. Minsky is pointing out that Sussman's fundamental assumptions on desiring to remove preconceptions is logically flawed.
Gotcha - I read it as Sussman didn't want to program his preconceptions into the network (for which randomness seemed suitable, which is why I was confused). Your explanation makes more sense.
