What is the test for a defense counsel to argue that a witness has a valid Fifth Amendment right not to testify?

"When a 'court determines a witness has a valid Fifth Amendment right not to testify, it is . . . improper to require him [or her] to invoke the privilege in front of a jury . . . . But where a witness has no constitutional or statutory right to refuse to testify, a different analysis applies. Jurors are entitled to draw a negative inference when such a witness refuses to provide relevant testimony.' [Citation.]" (People v. Morgain (2009) 177 Cal.App.4th 454, 466, italics added.) This, of course, explains why defense counsel did not object.