Ok, I'm probably going to be downvoted for this, but this is the expected outcome. They knew this was going to happen. Is it the good outcome? Obviously not. It is expected though. Orchestras, and I assume operas too, are very strict. You have to be in uniform, and you can't have anything that stands out. Even things like water bottles can't stand out, if they're even allowed those. You aren't allowed to do anything like this, regardless of if it's political or not. If it was just a sign that said their name or something the result would likely be the same.

Now, the opera should make a statement saying they support the stance. That would be good. However, members aren't allowed to do things like this. They agree to that when they join. This is more like a web developer putting a Palestinian flag on a website for a corporation they're working for than a rockstar being removed because venue owners complained. Sure, both people are making a good statement, but one of them is doing something that isn't allowed, and the other is just facing backlash by Zionists.