Regardless of how you can prove your innocence, it can be traumatic for you and your family, you can say goodbye all your computers and phone, you'd have to deal with the gossip from neighbours and relative and possible social exclusion, and possibly your couple/mariage as well.
The (new) developers of NightOwl have to do this because they understand that most users would never willingly participate in the trade they are "offering".
Ad-supported business models don't involve deception, the users understand the website/app/whatever is funded through advertising.
> NightOwl app cannot be held responsible in any circumstances for Shared traffic fees or any other costs the User may incur in accordance with agreements with their internet service provider. The Application use might be prohibited or restricted by the User's service provider or applicable laws. The Application may not be compatible with all service providers' policies and regulations. The User should confirm the ability to use the Application with their service provider.
So yes, they will absolutely suspend your account until they are satisfied the usage is in alignment with their expectations.
I'm not sure your ISP is going to delete your account because you didn't know some app was doing something shady. If the standard is every app user has to know what each app does under the hood, then there's going to be a lot of people who won't be able to match that standard.