You don’t have to agree with my opinion and it’s fine.
To me marching under a slogan is showing support for it, whether you understand the meaning or not. The burden is on you to know what you’re supporting with your action of taking part in a particular march and publicly associate yourself with people of certain views.
I don’t know if these slogans were present at the marches the poster attended, btw, I’m just giving my general opinion about how I perceive taking part in marches where certain slogans are present.
https://www.ajc.org/news/what-does-globalize-the-intifada-mean-and-how-can-it-lead-to-targeting-jews-with-violence
Or, to give an extreme but also unequivocal example, do you also think that people marching next to someone holding a swastika placard don’t necessarily support it, so it’s fine for them to be there and we should only judge those who actually hold the swastika placard and not anyone else who happens to be marching alongside them? Because, perhaps, they’re there for a different reason and just happen to be marching shoulder to shoulder?
We condemn people for attending certain gatherings where certain individuals are present without necessarily asking every single one of them what they think. Should we not be consistent?