It’s one thing to be interested in seeing political leaders, but if you are going to attend a rally, you are implying support: otherwise, attendance at rallies wouldn’t be seen as indicative of how much support candidates have. If he doesn’t support Ted Cruz, he could simply shut down accusations and state this.
If he doesn’t support him, then why not just say it? Cruz has views that are unpallatable to many people (including myself) — way beyond the realms of normal political debate. If a star attended a Neo Nazi rally, they would at least, be expected to denounce their ideas.
Richard Dreyfuss is both respected and has a likeable image that contrasts with those of Cruz, in many peoples’ eyes — hence the newsworthiness of the story. I would take the fact that this is news, as a compliment — people less respected, would not attract the attention that he has for his actions .
In my opinion, when you have a candidate proposing such terrible policies, everyone who shows support, is a legitimate target for criticism and he should state quite clearly if he does or does not support Cruz’s ideas, or let people assume that support comes from attending the rally.