Dear Sir,
A perusal of this judgment indicates that the HC has not laid down the law in general and has passed this exceptional direction only in respect of the parties in that case.
Please read the following concluding paragraphs:
"Consequently, the Registered Authority under the Hindu Marriage Registration Rules, 2002 framed under the Hindu Marriage Act, 1955, is directed to accept the application for registration of marriage of petitioner's daughter and son-in-law through their power of attorney holders."
"It is clarified that this order is made in the peculiar facts of the case as compelling the petitioner's daughter and son-in-law to visit India only for the purpose of registration would entail avoidable delay and expenses."
You can surely cite this judgment to convince him and if the Registrar is kind enough he will agree to your request.
Otherwise, as suggested in my previous answer, you can move a Writ Petition before Hon'ble Delhi High Court (as was done by the Petitioners in the case you have mentioned) or the Supreme Court (both are competent courts). The Court will issue a similar direction in your case as well.
For the procedure and formalities before the certificate issuing authority, you can read the following link:
http://health.delhigovt.nic.in/wps/wcm/connect/DoIT/delhi+govt/community/marriage+certificate+and+registration
For appearing before courts, it is always open to appear in person, but considering the situation we are in, the Petition will have to be filed online and the case would be heard via video conferencing.The entire procedure involves a few technicalities. It is recommended that you seek assistance of an advocate.
Best wishes.