The problem is that we cannot find any such rule aside from "the GM said so." ToS 3.3, which was cited per the first page, reads as follows:
"3.3 Profanity and Offensive Language. You may not use profanity or any language that a reasonable person would find offensive. The Game is for players aged 13 and older. You agree to behave accordingly."
This could, in theory, apply to brothels or selling ERP in PF since it specifically lists "13 years or older." It has zero grounding for any other instance. This also directly conflicts with previous input from another GM from earlier on, which should take precedence barring some kind of ToS change not listed on the web page I pulled up minutes ago.
The only other possible ToS issue could come from ToS 3.2:
"3.2 Disruption. You may not in any way disrupt or interfere with the Game experience of other players, including the disruption of Square Enix's computers and servers."
This is pretty broad by design, but it's a stretch to say that "scrolling to the very bottom of PF" is disruptive.
To quote the official Game Manual from Square Enix's website:
"The Party Finder allows players to recruit adventurers on the same World or data center who share common goals. It is also possible to recruit specific players to a party using a private party password."
That's it. That's all the official policy we can see. There is no mention of prohibiting PF from only using content. All it says is "share common goals," which RP advertisements fulfill.
It would be wonderful to get some official clarification on this, as nothing I can find makes this justified aside from heavy-handed (and poorly targeted) punishment with poor justification. If there is some rule I have missed according to the information publicly available to players, let me know. I know this change will hamstring the RP community and drive out many people to whom the RP community is their preferred content and why they keep their subscription up.
If there is no explicit rules justification for these punishments, I think disciplinary action on the GM and forgiveness of the unauthorized warnings is warranted.