Leftists are the most devoutly religious people in the world. They are primarily fanatical Jews, Catholics, Evangelicals, and others, who have replaced their 'religion' with the worship of Leftism.
Hawking is no different. His life used to be dedicated to pure science and mathematics. Lately, he has replaced his fervor for science with fanatical Leftism. It is inevitable that as celebrities lose their ability to perform, that they turn to Leftism to try to maintain the spotlight and some relevance.
With Hawking, I'm not sure it is such a loss. Like all the Hollywood Leftist before him, his career was coming to an end anyway.