I agree but 2.999999 moa is close enough to 3.000000 moa to be insignificant.
For whatever it's worth, that is a true statement.
The problem is that the figure in question (when combining 1MOA and 2MOA) is not 2.999999 MOA, it's about 2.24MOA. 2.24MOA is significantly different from 3 MOA--especially to someone who's concerned with precision.
You'd actually be better off in this case approximating the result by simply using the larger of the two accuracy figures and ignoring the other entirely than you would be by adding them together.