I think we are supposed to read between the lines.
Of course, if they intend to be able to keep the app running they can't say "this is to notify others to avoid the area so they are not caught" and they have to present it as a "notify my lawyers" kind of app.
But then why erase the contacts when message is sent if it is to notify lawyers? Is the identity of the attorney secret, how are they supposed to file on behalf of the client?
The example of message on the front page also kind of indicates the usage:
> "This is Julia’s last known location. Do not go there now."
Why emphasize the last known location in the app, but then admonish recipients to not go there.
It might be better if it is re-framed as an emergency location group broadcast app without focusing on immigration and lawyers. Maybe re-use the wording that those "life alert" systems use and then spread the app name through the word of mouth or other channels.
At best, though, it seems like it could aid a lawful purpose. I don't have a particular problem with it if that is even a fifth of the intended use case.
It doesn't help the person being detained, but it might help others.
It's right in the example message being sent (from the front page):
> "This is Julia’s last known location. Do not go there now."
The idea being that the person being detained, is being detained, but the can warn their friends and loved ones to stay away from the area so they are not caught as well.
It's basically a warrant canary. The purpose of a warrant canary is not to refuse to comply with the law: on the contrary, it only communicates something nontrivial if you intend to comply with the law!