You're wrong. Think about it. The code reads a value from a given address, which is always going to be a one or zero. This is traditionally called a boolean. And while a boolean could be fit into a single bit, bytes are the smallest common data unit, and it is more likely that Blizzard's developers simply used either C++'s intrinsic "bool" type, or C's "BOOL" typedef, both of which resolves to bytes. Therefore, an address that points to this byte, must therefore be a byte pointer. As a matter of fact, if you read the code, the address is placed in EAX, and then the code treats EAX as a byte pointer. Ipso facto, it's a byte pointer. While we're on the subject...
Code:
bool AreYouInGame() {
return (*(BYTE*)(0x6FAA1988));
}