I strongly suspect that the error rate shown is the impermissible threshold. They computed it at 2 out of 250,000 rather than 1, to show what the law won’t allow, then demonstrated the actual error rate far surpassed that requirement.
The sentence needs to be recast to become bulletproof.
Proggies are bastards who will use the most trivial to debunk.
Error rates are commonly reported as “plus or minus 1/250,000”. Note: the plus side is a measure of distance and the minus side is a measure of distance: therefore, 1 + 1 = 2.
So, being statisticians or mathematicians, 2/250,000 is probably indeed exactly what they calculated: the breadth or range of the error.