[SkeuomorphicBee]

On the "how to program more defensively" point, the author techniques are not meant to protect against malice (you are right that in such case of malice there is nothing that can be done), but instead to protect against foot guns, where innocent and reasonable changes in a module internals might unknowingly break another module.

I believe the author's arguments are quite valid, inheritance breaks the concept of a "black box" in Object Oriented Design. Once you inherit from a class, all that class internals become an "unadvertised signature", nothing is a black box that can be transparently changed anymore, any internal change may break a subclass.