I'd be interested in an answer to this from anyone, not just @Curlyboot - especially whether the donor who calls themselves "MolotovNextTime" would consider this an attack, and if you do insist on calling this attack a protest, at what point you think legitimate protest tips over into an attack.
I'm clear that it was an attack. It was clearly designed to cause alarm and distress, and to shut the conference down. That's an attack, not a protest. (And I think "MolotovNextTime" would agree with me on this, even if we agree on nothing else.)