They also act as access alarms[1]. Why even comment if you didn't bother to read the docs?

> The PAGE_GUARD protection modifier establishes guard pages. Guard pages act as one-shot access alarms. For more information, see Creating Guard Pages.

[1] https://learn.microsoft.com/en-us/windows/win32/api/memoryap...

Guard pages are for the process that creates them, they're not for the other processes that try to read the memory.