I don't think SEC is measuring decentralisation by counting full nodes.
Also, technology is important like if a coin is scalable and scalability is making it decentralized.
You pretend to know much more than we do. Could you tell us
1) what algorithm does SEC use to perform the analysis of the technology?
2) how does the result of this analysis influence the decision of SEC to declare a coin security now or any time later?
3) what is a legal definition of decentralisation used by SEC?
4) what is a legal definition of scalability used by SEC?
5) is it possible that SEC conceal information about its procedures from the public?