Sh.Alkesh Jani Ji,
What is brewing in your mind I know and what is brewing in my mind you know very well. Even then I intend to answer to your question on this public forum. My views may not be okayed by you or other experts/readers but it is my moral as well as ethical duty to answer your question as I have strongly supported the views of Madam Shilpi Jain.
(i) RWA is a person as per Section 2(84) of CGST Act. Not in dispute.
(ii) In case RWA's maintenance charges are less than ₹ 7500/- and annual turnover is less than ₹ 20 lakhs, RWA is exempted from GST. If exempted from GST, no need to obtain registration. Not in dispute.
(iii) As per Section 24 (iii) of CGST Act, compulsory registration is for those persons who are required to pay tax under reverse charge. Not in dispute.
(iv) If service provider (security agency) is individual, firm, trust etc. recipient is liable to pay GST under RCM but if the recipients is unregistered (may be virtue of value based exemption), the service provider himself is liable to pay. Here RWA is out of gamut of Section 24 (iii) . RWA being legally unregistered.
(v) Now liability is on provider of security agency and service provider will pay GST only if his turnover is more than twenty lakhs. If his turnover is less than threshold limit, he will also not pay GST.
(vi) Security Service has been brought under RCM w.e.f 1.1.19 but brining this service under RCM is subject to the conditions laid down in the RCM notification.
Hence in this scenario registration is not compulsory for RWA and RWA is not liable to pay GST.
These are my views in response to your question. With due regards to you as I consider you a very very knowledgeable person.
Difference of views is meant for welfare of all the visitors.