The best I can offer you is explicit example text. Given the quality of examples in RQG, I understand if that's not enough (there are many obviously incorrect examples in RQG), but it's all we have.
What? No! You need 11 pts-equivalent to penetrate the 5pt Shield (this could be a boosted Dispel, but I'm sure we agree about that), but only 10 pts to Dispel it.
But in the example, it's about what it takes to Dispel Countermagic, so it's a given that the Countermagic is in place. The obvious interpretation is that the Countermagic doesn't protect itself.
If we go by your interpretation, an 9pt Dispel would be enough to get rid of 10pt Countermagic (because it's one point less, and that removes both spells by Countermagic text). This strikes me as super weird.