Without excusing anything, the bit too readily missed about the 1919 Amritsar massacre was the febrile state of politics after German and other external assistance to Indian Nationalists barely 60 years after the Mutiny. Compare and contrast the 1916 Easter Rising. Crowd control and minimum force were born in the 60s after events like Kent State shootings and, for us, developed through NI and various London riots.
Think about the tools, tactics and training….lethal force was the only thing available after a stick. Did I mention the ones doing the shooting were Gurkhas? They weren’t obviously reluctant…. Dyer was only ever going to be a butcher or the guy who lost India. Tough gig as it turned out.
Sikh terrorists were a problem in Canada after Indian Army operations in the Golden Temple in 1984 (Air India 747 downed off Ireland in 1985 killing 329). It sounds like the suspect has mental health issues as much as anything. UK Sikhs are overwhelmingly sound as a pound. Good people.