Or bitwise OR and XOR operators, according to the article? That's a bit hard to believe, no pun intended.
bool a = true;
bool b = true;
bool c = a + b;
Either way it's highly nonstandard not to implement a bitwise-or operation on a boolean type. It's a violation of the "principle of least surprise" as well as a portability hazard. No upside that I can imagine.
I get suspicious of being fast and loose with conversions between int and bool. This is implicitly required when working with operators like &&, ||, ==, etc., and working with pre-C99 bools and library typedefs. But assigning anything other than 1 or 0 is asking for problems. There is a whole class of bugs that shows up in security bugs involving assigning someone's machine-word-sized Boolean expression into someone else's byte sized bool, losing bits, and flipping from true to false.
I sometimes feel there is a ^^ operator that should be there and is missing, in the same way that we have && and || corresponding to & and |. I have occasionally faked it with a macro:
#define XOR(A,B) (((A) ? 1 : 0) ^ ((B) ? 1 : 0))