It's not a load into the exclusive state because from the perspective of the rest of the system, nothing has happened yet.
@thomasts, just to add on, to is probably accessing C from memory as a bus read so the load into exclusive state does not happen.
Here we use lazy versioning. So the value 5 is not assigned to C yet, and C is accessed with a BusRd. Only when committing and we're really trying to modify C with 5, BusRdX is sent.