It seems to me pretty clear that it may not, because such picketing -- whether related to labor issues, the merits of the movies the theater was showing, or whatever else -- is protected by the First Amendment, at least in traditional public forums such as parks or sidewalks.
The law may restrict the volume of the picketing, or the size of the group, especially if there's a serious security threat that may stem from the presence of a large group, or if the group is likely to block pedestrian traffic. In some situations, the law may create a 36-foot buffer zone if there's a serious risk of picketers' blocking entrances, and narrower restrictions have proven unavailing. The law may also require that people not approach within a few feet of a particular person to talk to the person without the person's permission. And the Court has upheld restrictions on residential picketing, stressing the special role of the home as a place where people should be able to retreat from controversy. But as a general matter, people -- especially in small groups -- are free to express their views in front of places of commerce and entertainment, even when offended listeners might be present.
The Ninth Circuit, though, held last week (Berger v. City of Seattle) that it's constitutional to ban speech to strangers -- even speech by one person -- within 30 feet of "any captive audience," including "patrons waiting in line for events" or eating in a seating area. The particular rule involved restrictions in a park, but a city sidewalk is just as much a traditional public forum as a park.
So this means that picketing, demonstrating, and the like, on city sidewalks -- even when engaged in by one person -- can be forced 30 feet away from any movie theater line, any outdoor restaurant seating area. Likewise, I take it that such speech can be forced 30 feet away from any employee whose job requires him to stand near a sidewalk, for instance a hotel doorman, an employee working as a sidewalk vendor, a maintenance worker, and the like. Those employees are, after all, even more "captive" than diners or people standing in line.
What's more, the court read Madsen's authorization of a 36-foot buffer zone outside an abortion clinic entrance as being justified by "captive audience" concerns related to "women entering an abortion clinic." The Ninth Circuit thus seems to suggest that an audience may be "captive" even to speech that it only needs to see briefly. If that's so, then any picketing or demonstrating outside any business would be seen as involving a "captive audience" of business employees and vendor employees who have to come and go through the front door, and perhaps of customers, too.
This strikes me as a pretty clearly mistaken result. It might not have been intended by the judges in the Ninth Circuit panel majority, who were talking about restrictions in a park and not on a sidewalk -- but, as I mentioned, parks and sidewalks are both treated as the same sort of place by First Amendment law (a traditional public forum), and if a restriction is allowed in a park, it would presumably also be allowed on a sidewalk. (If anything, restrictions on sidewalks may often be more justifiable because pedestrian traffic problems tend to be more serious on sidewalks.)
Moreover, while the particular plaintiff in the Ninth Circuit case was a street performer who made balloons, apparently performed magic tricks, "talk[ed] to his audience about his personal beliefs, especially the importance of reading books," and seemingly accepted contributions, the panel's rationale wasn't limited to people like plaintiff (nor am I quite sure just how it could be so limited). The panel upheld the captive audience rule on its face, and treated it (in relevant part) as banning "speech activities 'within thirty (30) feet of any captive audience ....'" It did not limit its decision to rules banning speech activities that solicit (expressly or implicitly) the immediate handing over of money, or to rules banning balloonmaking and magic tricks but allowing political or social advocacy. The decision is thus a precedent for restrictions that cover many more people than "Magic Mike" Berger.
Finally, I should note again that the Court has indeed accepted some kinds of restrictions on picketing in public places, as I said in the second paragraph of this post. The Ninth Circuit's decision is thus not a completely radical new step. But it does go far beyond, I think, the narrow restrictions that have been upheld, and covers speech that poses no real security risk, no threat to individual privacy, no material threat of blocking entrances, and no inherent danger of people trespassing on others' personal space (this is a 30-foot exclusion zone, not a requirement that one stay 8 feet away from people whom one is approaching).
And to the extent that one does see this as a logical extension of past decisions, that should be a reminder that the slippery slope from narrow restrictions to much broader ones is a real risk in a legal system that's built on analogy and precedent. Even when the precedents by no means require a particular result, and even don't justify it in the minds of many, some decisionmakers (here, judges) may read them that the precedents may end up justify many more restrictions than the precedents' drafters contemplated.