> What change was the person who shot him hoping to elicit?

We don't know yet, but we can infer these possible changes "the person who shot him [was] hoping to elicit":

- stop an effective communicator from further moving the needle of public opinion in his side's favor

- intimidate other effective communicators with similar views

- intimidate other future possible effective communicators with similar views

- cause more violence (some people love chaos and violence)