Nothing illegal
Cloudflare is a CDN provider. Being a CDN provider they have servers located all over the world. Cloudflare also has servers hosted in airtel Data centre; hence any traffic from Cloudflare to the back end network they are trying to reach will pass through Airtel network; and hence be subject to the policies we lay down for blocking (approved as per Governments Department Of Telecommunication)
In this case the certificate that is shown is cloudflare’s. However when Cloudflare attempts to make a connection to thepriatebay.org this is being done over HTTP. Hence Airtel is able to inspect the request and check if it is being made to a website that is part of the block list. Since thepiratebay.org is a part of the block list, airtel blocks this request and inserts the default blocking message (http://www.airtel.in/dot/)
Hence given that Cloudflare servers are hosted on Airtel network and Airtel is mandated to block traffic to thepiratebay.org don’t see anything wrong / illegal that is being done.
Good read, but incorrect facts with Gas