The Saudis don't have a Law of Succession in the same way the Brits do.
The country is like a family business and the offices and profits are split up according to internal family power struggles.
For instance, a brother usually inherits, rather than a son.
I think it's a mistake in the article.
There's a whole book written on the subject. Here's a summary. (It was published in 1995, so add some years to the ages.)
AFTER KING FAHD: Succession in Saudi ArabiaThe ruling family of Saudi Arabia, one of the United States' most important allies in the Middle East, is heading for a crisis of leadership. Despite its modern infrastructure, paid for by huge revenues from oil exports, the kingdom's political system remains rooted in tribal structures that have scarcely evolved in the last several hundred years. Control remains tightly, although not always firmly, in the grip of the Al Saud clan, which, almost alone among the global roster of nations, incorporates its own name into the formal title of the state.
King Fahd (b.1921), whose twelve years of rule have been marked by periods of prosperity, extravagance and more recently, fiscal restraint, is 73 years old. His attempts since 1991 to bequeath a legacy of a more modern political framework and wider forum of political consultation have raised more questions about the issue of succession than they have answered. The process of succession is a murky system in which the throne passes down the line of Fahd's many brothers, while members of the next generation watch tantalized, wondering what stroke of fate will eventually give them (or a cousin) power.
Crown Prince Abdullah, who is expected to take over when King Fahd dies, is over 70 years old. Virtually all Saudi kings have begun their reigns in their fifties or early sixties and have all died in their early seventies. Furthermore, the next likely candidate after Abdullah is Sultan, who turns 70 this year. Sultan's next five oldest brothers are all already over 60.
The kingdom is therefore facing the prospect of having to appoint a new king every two or three years. Were Saudi Arabia unimportant in the world or its king a purely constitutional monarch uninvolved in the everyday business of government, this might not matter. But the king of Saudi Arabia makes virtually all the important decisions in the country, either personally or as prime minister and chairman of the council of ministers, which functions as the kingdom's cabinet.
An additional and recent complication is that King Fahd is showing increasing signs of poor physical and mental health. Although he might remain king in name, the possibility is growing that the everyday responsibilities of government will be passed on to his immediate brothers.
The process of succession, as it is commonly understood, is supposedly a smooth one, with the throne passing from brother to brother through the line of sons fathered by the founder of the kingdom, Abdul Aziz (often referred to as Ibn Saud). The process has already been used in a variety of different circumstances -- death by old age, deposition due to incompetence, and assassination. But the historical record shows that this apparent smoothness masks fierce intra-family rivalries that often fester for years. In the 250 years in which the Al Saud family has often dominated the Arabian peninsula, such rivalries have occasionally led to interruptions in its rule. Also, the notion that King Abdul Aziz wanted each of his sons to rule in turn (if they were able) is a myth. The process is a far more raw quest for power.
Succession in the future may well be complicated by the interests of Ibn Saud's grandsons, whose claim on the throne was recognized by King Fahd in an edict in March 1992. These grandsons, many of whom are already middle-aged with some holding important government positions, do not yet act as an independent constituency, but they are known to question current assumptions about the succession process. Such is the centrality of power held by the king, and such are his powers of patronage, that maneuvering for future successions is already an active part of royal family politics.
Succession -- or rather, squabbles over it -- could greatly affect the closeness of ties with the United States, which constitute the kingdom's most important international relationship and are among the most critical to U.S. economic well-being. However, due to the insularity of the royal family and its inbred fear of foreign encroachment on family prerogatives, Washington can only affect Saudi succession on the margins of the kingdom's internal decision-making process. In the interim, U.S. policymakers should take steps to prepare for any number of possible eventualities in a succession process whose outcome is not assured.