The world is not as rigid as northern Europe thinks it is...
Far more rule and law-bending is happening than that, for the possibility of "inventing a new grade" to be really impossible/surprising.
The only problem was they legally had to go through a open contest for the position.
So when someone came up with 5x the qualifications (citations, papers, conferences, better universities attended, etc, globally too) than their ho-hum friend (some relative of the dean), the professor body suddenly folded the position.
A few months later, they announced a new opening, with some specially crafted qualifications, so that only their friend could pass.
> In 1994, the A* grade was added above the grade A, to further differentiate attainment at the very highest end of the qualification. This remained the highest grade available until 2017.
The grades are now 1-9, with 9 being the highest and above A*.
In this particular case, I think it certainly is within a University's remit to award a special grade given the exceptional circumstances.
Another example of the US inching toward the metric system ;-)
Although yes, the UK too is in this hybrid world where gas (petrol/diesel) is in litres, temperature is in Celsius, but vehicle speedometers are in miles per hour and feet and inches are very popular for height, measuring rooms and furniture, etc.