Based of your tl;dr would you say they that the original assertion was true in practice, that they generally "can't publicly gather to protest Israel's actions either, not legally anyway."
You are allowed to protest against Israel, but you have to be extremely careful about how to phrase it, as a lot of things can get you arrested for anti-Semitism, even when it is arguably factual. So things like calling Israel an apartheid state, calling Israel fascist or warning of a genocide might land you in jail.
So basically you can protest legally as long as you don't protest against certain things the government protects. I'm gonna stand by my original assertion. It's like saying you can publish whatever you like in China as long as you don't mention Tianamen Square.
I'm not sure whether there have been any pro-Palestine or even simply "anti-war" protests that were properly registered, not disrupted and not dissolved by the police but I guess it depends on your definition of "legally".
I would say in practice it's very difficult to have any protest opposing Israel's actions in Gaza without a high risk of ending up in a place where the police decides to dissolve it. But I think in practice the two biggest reasons for that are a) the topic is likely to attract protestors who decide to express opinions that are illegal (or are deliberately interpreted that way) and b) most protests tend to be dissolved by the police eventually because even ones that follow all the rules usually spin off or feed into spontaneous protests that don't.