Aye, I figured the specific 'listed in core army list' restricted it to DA, Eldar and BA at the moment who's SC's are in the HQ of the core army list.
Anyway, the other weak thing at the GT last year was a BA player taking Inquisition allies despite it supposed to be 'options only from the army Codex'.
Frankly, it allowed hard-core armies like BA to cherry-pick the best bits from Inquisition books, meaning the very few competitive incentives for a GK/ Inquisition/ Sisters army were stolen.