I think that studying math and becoming a math professor would put you in an excellent position to work toward preventing an unfriendly AI. First of all, you could, if you chose to, study computer science and artificial intelligence at the same time. Second of all, you will be in a position to influence others who may some day be working in the field. You can start a LessWrong chapter at the university you attend and the one you teach at. You can lecture/talk to your students at the importance of caution and safe guards in what ever they work on in the future.