One of the intentions of the legislation is to create a system whereby the owner understands the responsibility and takes the necessary action in the case of a hazard or a wreck resulting from a maritime casualty. Having discretionary power for either minister, their officials, and other designates and delegates ensures that all information available is taken into consideration in the determination of what must take place. Vessel owners need the opportunity to act if possible. The minister has the discretion. If the minister needs to act, that discretion exists. Discretion not to act by anybody is not necessarily the connotation that I understand from “may” that you're mentioning.
On February 26th, 2018. See this statement in context.