Some of the examples are somewhat formally true in theory and bullshit in practice; some are quite hallucinatory.

  - Creating a potentially troublesome misaligned int pointer is a precisely localized and completely explicit user mistake, not something that just happens because it's C.
  - Passing signed char to character classification functions that expect an unsigned char (disguised as an int) is a very specific dumb user error. The C standard could specify that all negative inputs, including EOF and invalid signed char values, are classified as not belonging to the character class, but I doubt the current undefined behaviour in isxdigit() etc. implementations ever went beyond accepting invalid inputs.
  - Casting floating point values to integer values in general requires taking care of whether the FP values are small enough to be represented and what to do with NaN and Inf values: not the language's responsibility. C offers a toolbox of tests, not ready-made application specific error handling.
  - Expecting C to handle "address zero" in physical memory in ways that conflict with NULL in source code denotes a complete lack of understanding of what a program is. Where stuff in an executable is loaded in memory, in the rare cases when it matters, can surely be affected with platform specific extensions, possibly at the level of linker commands with nothing appearing in the C source code.

They are true but I agree it's not a great article. C has an unending list of UB and given the title I was expecting a more comprehensive survey, but they actually just picked a few that are both fairly well known and not very interesting.