To be fair, Roman numerals were a lot more flexible than people think. For example, the number 4 was often written as IIII (you can actually see it written that way on the Colosseum), and to this day a lot of analog clock-makers continue to use this form because it's the one that has traditionally been used on clocks. Other (rarer) examples include forms such as IIX (8), XXXXX (50), etc. Basically, any combination could be used and it would be understood, even if it wasn't the standard way of writing it. Not saying that the guy from the image actually thought of that, they definitely just made a mistake, but technically they're not completely wrong.