Perhaps another way to explain why clause 17 exists is that it essentially gives the minister the power to regulate a behaviour, just like regulations would otherwise. It's just that there's no time to develop regulations when a threat is imminent.
The words, “anything that in the opinion of the Minister it is appropriate to do or refrain from doing in order to respond to the threat” are very broad in scope and certainly allow the minister to say, go on that property and do this to address the threat.