That's a valid translation given the history of far-left terrorism in Japan, and the terms used to refer to it in Japanese.
The original Japanese describing the terror incident is "セクトによるテロ事件". The word セクト (literally, "sect") was very frequently used to describe extremist groups like the Japanese Red Army or the East Asia Anti-Japan Armed Front that carried out terrorist attacks in Japan in the mid-to-late 70s, and their descendants.
The twitter thread I'm partially excerpting here is a good broad read of it, given the context of when the work was created. While you'd be justified in translating this either way, this is absolutely a situation where proximity to the studio creator would be useful to knowing which sort of terrorism it was intended to refer to.
For what it's worth, when I do a Google search for セクト and テロ事件 (terrorist attack), the Japanese-language results are about far-left terrorism locally, and radical Islamic terrorism abroad.