Robert M Watson Jr
From IAF regs
Article 9 : QUALIFICATIONS FOR CONDUCTING EXAMINATIONS AND MAKING RECOMMENDATIONS 1.An Aikido organization with Hombu Recognition, when its Person in Charge is 6th dan or above, may conduct examinations from 1st dan to 4th dan. When the Person in Charge is 4th dan or 5th dan, it may conduct examinations from 1st dan to 3rd dan. In the case of a 4th dan examination, an application to Hombu must be made. and the examination will be conducted by the Hombu or a person delegated by the Hombu.
What the "rules" are how reality functions are always subject to wide interpretation. Ethical behaviour is suppsoed to narow that gap - either by altering behaviour or changing the rules.
Of course, that's what the rules say. The thing with Japanese organizations like the Aikikai is that "rules" are more commonly treated as "guidelines" by the folks in charge.
I wouldn't count on them too carefully - in the end it's all up to Doshu, and the decisions don't always follow what's on the website.