I guess the fear is that normal and innocent sounding goals that you might later give it in real world use might elicit behavior like that even without it being so explicitly prompted. This is a demonstration that is has the sufficient capabilities and can get the "motivation" to engage in blackmail, I think.

At the very least, you'll always have malicious actors who will make use of these models for blackmail, for instance.

It is also well-established that models internalize values, preferences, and drives from their training. So the model will have some default preferences independent of what you tell it to be. AI coding agents have a strong drive to make tests green, and anyone who has used these tools has seen them cheat to achieve green tests.

Future AI researching agents will have a strong drive to create smarter AI, and will presumably cheat to achieve that goal.