It's the style guide for Google's specific environment. If you are not Google, much of it is likely irrelevant.
For example, the style guide says that C++ exceptions are the way to go...except that by the time the guide was written there was already too much existing code that wasn't exception safe. Therefore the guide says that regretfully, exceptions cannot be used.
And this is why the guide is "bad" - you simply can't avoid dealing with exceptions in C++ code, unless you also forgo the Standard Library, use weird and unreliable methods to detect constructor failures, and a bevy of other problems.
For example, the style guide says that C++ exceptions are the way to go...except that by the time the guide was written there was already too much existing code that wasn't exception safe. Therefore the guide says that regretfully, exceptions cannot be used.
Edit: clarification