We shouldn't get too worked up when brands talk up their own credentials; branding is about bending reality.
In the case of Audemars Piguet, they also use movements developed for them by Vaucher Manufacture. This facility is part of the Parmigiani group in Fleurier, and supplies many high-end brands. Another Parmigiani facility builds and finishes dials for brands that don't disclose this information to their customers.
There's nothing wrong or surprising with any of this. If it does appear off, then it's because customers too easily believe the spin that touts such things as in-house and hand-finishing as markers of exclusivity.
Ultimately, it's about liking a watch as it looks and feels. If we want to be sure that what we're holding and looking at is truly hand-finished, the best way to do it is to support small volume independent brands. Audemars Piguet, Patek Philippe and co. by contrast make watches at an industrial scale.