... Anyone provide more factual info with this and whether this is right or wrong?
Dale, this is not correct. There is no such rule because there CANNOT be any such rule.
Cannot, because if there was such a rule, it would be frequently broken - without the PIC able to do anything about it.
Refer back to the example I gave earlier. If place B is remote then there is a good chance that the aircraft will not have the option of diverting or holding.
This is why there cannot be any such rule.
For those really remote places like Norfolk, Christmas and Cocos Islands, the rules have a special way of making sure you have diversion fuel. That is the "remote islands policy".