"TCNs are orders that require a company to build new capabilities that assist law enforcement agencies in accessing encrypted data. The Attorney-General must approve a TCN by confirming it is reasonable, proportionate, practical, and technically feasible."
It's a step above a warrant, as an order, when building a new capability. But yes, its focused in on one case. As to "reasonable" - our current AG is a strong supporter of expanding government powers as a way to fix any new problem that appears. He's done some good. And some bad. It isn't hard to see him rubber-stamping these, if someone across the hall needs it done.
Also... If a TCN order comes through, you're not permitted to tell the business that you've been ordered to create a backdoor in them. And they can order random anyone in the company to comply - it doesn't have to go to the C-level.