It's important to note that there are two aspects to this.
As you note, there's the process that follows from the decision, but the process is based on the information. Therefore, the movement from section 25.1 to 25.2 to 25.3 is an escalating view of the national security evidence. It moves from a concern that there is a national security consideration worth evaluating—and that's the beginning of the process—and that it could be injurious. It's the information that makes the determination on whether or not it moves to the next step. What this does is that, essentially, in process, it makes a determination without the information that it must proceed to the next step.
You are correct, though, that it does not bind the minister to an outcome based on that information. However, normally sections 25.1 to 25.2 to 25.3 are additional information and further scrutiny on the basis of the new information that follows, because the information is actually a further assessment.