This can be instantly disregarded because Steve Gibson is a charlatan. He's got a history of getting things wrong as loudly as possible in order to generate reputation. http://attrition.org/errata/charlatan/steve_gibson/
They're bits. SYN can be represented as 0x02, ACK can be represented as 0x10. 0x02 BITWISE-OR 0x10, ie SYN BITWISE-OR ACK or 'SYN-ACK' colloquially, is 0x12.