The sentence about five individual Members is intended to prohibit any company or organization (whether a Member or not) from obtaining de facto representation via individual Members. That is, the rule is not limited to five individual Members who are Member Representatives.
The rule could be made clearer by saying "as representatives for the same company or organization" rather than "a company or organization". (In case anyone reads "a" as "any".)
One could argue that normative rules do not belong in Definitions. The five-Members rule doesn't have an obvious home in the Process doc (perhaps the JSPA?). The "Spec Lead" definition has a redundant rule as noted elsewhere. The definition of "Profile Specification" contains clauses that would be better in 2.1.3.