There are many actors and players who serve in many way but need not join in any political party.
Politics is not mere participation in election. Very few know that A.K Hangal, a well known character artist is member of national council of communist party of India. His views are respected. Similarly, Balraj Sahni was a communist Party member even though he was never in election politics. However, he was never given any award by Government of India because of his political affiliation.
By discussing various issue of statecraft and national interest, we also participate in politics without indulging in elections.
Amir is definitely engaged with politics by raising issue of national importance. In this connection, I may add that even Prime Minister cannot do all that he desires whereas any citizen can get something done by raising his voice with determination.