The first five pages are the table of contents, definitions of acronyms, and then about a 10 page explanation of background and what CISA is required to do by the law. Starting on 98 there is also an analysis, as required by law, of who is affected, what the cost of implementation is, and a wide variety of other details to inform the public on why this on rule and this way. That cost includes what it will cost CISA to implement the rule (e.g., CISA estimates that a covered entity would spend six hours per submission to collect, store, and maintain records ... hourly compensation rate of $35.19). It analyzes this rule for people who might want to critique it from a variety of perspectives and an enormous amount of potential impacts as required by law (e.g., its compliance with technical standards, energy usage, tribal implications).
Its easy to jump on these things for being long, but I would imagine the goal is to be thorough and precise. That matters to making this useful - as it does any law or regulation.
Doing government well is hard...just like writing good code or designing any complex system is hard. Documentation is often, and more often should be extensive. The headline is a cheap shot meant to undermine the actual rule itself.