Earlier quoted context omitted.
IQ as a precise, cross-comparable measure? Sure. As a conceptual shorthand to describe the concept of intelligence? No.
The previous comments were talking of IQ in a quantitative way ("x points less"), so they fit in the first definition. Even the second definition is not really a thing. Intelligence as a concept doesn't mean much and needs to be defined properly. Using it this way is just another way to divide people superficially.
I read that as a within a single individual, case A (no brain damage from cause C) vs case B (with brain damage from cause C), where using it as a shorthand for intelligence differences within a single individual makes it a useful shorthand for most readers, IMO.