Umm...what? The first person just picks a number, there's no RNG involved, no need to tell anyone a range. I know we're taught to plan for edge cases, but I find this pretty silly.
edit: Nevermind the second point, I basically echoed what run4yourlives said - I think the averaging somewhat defeats the purpose. "Political stability" is the whole reason they ask not to disclose salaries in the first place.
I'd be more comfortable with a real random (at least pseudorandom) number. Humans are terrible at generating random numbers and information could be given away on account of this. For example, people tend to favor 5s and 6s when generating "random" large numbers.
edit: Nevermind the second point, I basically echoed what run4yourlives said - I think the averaging somewhat defeats the purpose. "Political stability" is the whole reason they ask not to disclose salaries in the first place.