Hmm, call me stupid, but I'm thinking along this way:
1. They show 5 systems at the beginning
2. Eliminate 2 extreme ones, leaving oligarchy, republic and democracy.
3. Oligarchy is bad, so that leaves republic and democracy
4. Democracy is bad too, so the only proper system is republic.
Hence my conclusion (unless I'm thinking illogically)... not that the above thinking is wrong, I just simply see it as another political propaganda spiced with bits of history.