Dealing with issues that could affect a celebrity’s personal brand takes a lot of thought. Many celebrities have public relations people to deal with most of their charity work — Taylor Swift even had a spokesperson speak for her donation to Kesha. It’s only celebrities who are well versed in certain subjects who find themselves able to directly speak out against high-profile incidents like Kesha’s. This limits the amount of damage their image takes, because they begin to incorporate these issues into their personal brand. In fact, Lady Gaga released a song explicitly about sexual assault last September.
I think celebrities should have a voice about dangerous fans. However going to the police first and waiting until the problem gets fixed by the police or lawyers or whoever in private is a good idea first. Stalking is a serious matter whether a person is a celebrity or not and should be treated as such.
I really don't understand why celebrities aren't allowed to speak out about their own harassment. Stalking is a crime no matter who your target is, and people who stalk and/or otherwise threaten people who are famous tend to go to dangerous extremes. Are celebrities supposed to sit back and take that just because they're famous? I wouldn't. Being silent can be dangerous, too.
Celebrities frequently serve as role models for the general public due to the visibility and attention afforded them. By speaking out publicly against dangerous fans, they will influence other fans and discourage them from similarly engaging in dangerous behavior. Celebrities should occupy a key role in positively shaping the general public's actions.