Quoting the same passage from the book (emphasis mine):
One of the benefits of detecting problems as soon as you can is that you can crash earlier, and crashing is often the best thing you can do. The alternative may be to continue, writing corrupted data to some vital database or commanding the washing machine into its twentieth consecutive spin cycle.
...when your code discovers that something that was supposed to be impossible just happened, your program is no longer viable. Anything it does from this point forward becomes suspect, so terminate it as soon as possible.
When a programmer uses an assertion, they're saying "This should never happen." Normally, terminating the program under these conditions is an appropriate response, especially since the programmer's assertion has been violated for unknown reasons. This is as true of a program with a GUI as it is for a console program or service.
For normal exceptions, the question becomes the same as it's always been: can we meaningfully recover from this exception? That depends; did the exception occur during a write to a critical database, or did the user simply give us a file name that does not exist?