Is this some elaborate way to hype up AV business so the new girl can get in to it while making it look like it is for some profund reason and not money?
Yep, that's the gist of it. The author is using Saori's peculiar circumstances to glamorize doing AV for Kaori and the readers.
Saori, a refined lady from a distinguished family, feels oppressed by her family and decided to do AV so she wouldn't have to be forced into an arranged marriage. Basically, she wants her family to find out that she does AV through someone else and apparently, she wants a potential fiancé to identify her. If you want, see
my post on the forum about chapter 73 where I talk about her plan.
Obviously Kaori doesn't know all this. Kaori, an insecure girl with a sense of inferiority associated with Yoshioka (even though she won the contest for Takeru), seeing a distinguished lady like Saori doing AV and looking so happy while doing it, must be making Kaori think, "Wow! doing AV must be incredible! I'm really curious about AV!".
The question is: Does this all work? Not for me. Even though this is classified as Erotica, it's all so implausible that it breaks my suspension of disbelief.