""The smoke was dispensed from air-burst shells. It would not penetrate roofs or walls. In the video it can be seen bouncing off roofs.""
How then did it burn patients within the Hospital, which has been attested to by doctors and other eye witnesses?
And killing those young (as you pointed out National Servicemen aged between 18 and 20, and totally lacking in combat experience) was indeed terrorism, however much YOU may disagree.
The British government thought so too, and called it such. I reckon they knew more about it than you.