My problem isn't that people have divided opinions on this. My problem is that people who oppose it write as if they're just now discovering that the opposite opinion exists --- in one case on this thread, someone suggested that the only reason Matthew Green held this opinion at all was political.

A serious argument against deniable messaging would start by acknowledging deniability as one of the shibboleths of the field of messaging cryptography, and then tackle the idea. Nobody on this thread has done that, and I think the reason why is that they're simply not aware that there is such a field.