For the record, while the revelations will likely be of interest to Touma (and everyone else) there probably won't be an opportunity to use Imagine Breaker. Sentience will discourage in-fighting, but there will be combat against NPCs that characters can optionally participate in / get hurt by, so you can handwave an injury that way.
Now for the copy-paste:
As mentioned here and here in the Q&A, no one will know what is going on before the plot is already underway. No one will be permitted to talk about their theories out loud; they will only have Sentience's word that they are planning a party. So whether or not your character supports Acumen vs Sentience, or is interested in starting a rebellion, is not strictly speaking relevant! By the time what Sentience is doing is obvious, it will be too late to back out or to join up.
If your character would hear "We're planning a party" and be suspicious or curious enough to stay and get themselves involved in something potentially dangerous that they know absolutely nothing about, that's fine. And if your character just wants to chat in the first mingle and leave before any action begins, that's fine too! I just want to make sure that everyone is aware of the level of commitment based on... absolutely no facts!