Can you elaborate many of who have been saying what exactly?
Is it:
All of those who condemn Hamas at Pro-Palestine rallies are shouted down?
Most?
Many?
Some?
A few?
One?
Usually when one writes “Those who..” without a specifier, it is implied you are speaking generally, as in most or more.
Who has assured you that “this is not the case” and under what terms did they do so? Assured you that most are not shouted down? Or that they hadn’t seen it ever happen? Or that it never happened and never would in the future?
Do you have any other recorded instances prior to today?