It seems like the point the OP was driving at is that Schneier's statement is a subset of that maxim. While Schneier's point is certainly important, the general

It seems like the point the OP was driving at is that Schneier's statement is a subset of that maxim. While Schneier's point is certainly important, the generalized form of "systems are not perfect, work with it" is more widely applicable. He wasn't ignoring what Schneier said, but agreeing with and building on it.