What is the test for denying a person a right to exercise their freedom of speech?

". . . even though a person has no 'right' to a valuable governmental benefit and even though the government may deny him the benefit for any number of reasons, there are some reasons upon which the government may not rely. It may not deny a benefit to a person on a basis that infringes his constitutionally protected interests especially, his interest in freedom of speech. For if the government could deny a benefit to a person because of his constitutionally protected speech or associations, his exercise of those freedoms would in effect be penalized and inhibited. This would allow the government to 'produce a result which (it) could not command directly.' Speiser v. Randall, 357 U.S. 513, 526, 78 S.Ct. 1332, 2 L.Ed.2d 1460. Such interference with constitutional rights is impermissible. . . ." Id. at 597, 92 S.Ct. at 2697.