They want Tiger to be removed (whoever has appealed) is only because they want approval to start industries in all those land that is declared as tiger reserves. Like you said, Lion is only seen at one place i.e. Gir Forest that too Gujarat which clearly means those opportunists are eyeing on all the available land for real estate sake.
Tiger being selected as national animal was mainly to help the worldwide cause of saving tigers from getting extinct. Even today after Taj Mahal, Tigers are the main attraction of tourists in India.
And it's not in the hands of Modi to decide but the Indian Board of Wildlife to decide that. The bad scenario is the committee that reviews & proposes this appeal has been filled by Gujaratis or to say supporters of Modi. That's why when this appeal was rejected without any thought in all the past years, this time a committee has considered it enough to propose it to the Govt.
India is not just Gujarat. There is a limit for every stupidity. They've been elected to give a good government dealing with actual problems. Is Gir alone the revenue generator in case of wildlife reserves to name Lion? It's due to the Tigers they're getting majority of their revenue.
All thanks to this government, they've succeeded in separating kids by making all muslim kids uniform as green, hindu kids saffron, christian kids white.