JRPGfan said:
Lafiel said:

the anti-virus measures definitely didn't "set him off", but the state of affairs might have provided him the opportunity to act out his fantasies he clearly had beforehands (which is why he had police-disguise at the ready)

Any prior mental health issues?
It should be a policy not to tell weapons to these people, and/or if they had ones (guns) before a mental illness, to have them taken away by someone,
once they get such.  Crazy person + gun = bad combo.

Likely, he had prior violent offense

https://globalnews.ca/news/6848816/nova-scotia-shooting-gunman-assault-2001/

Matthew said he was just 15 years old when an allegedly drunk Gabriel Wortman assaulted him outside a denture clinic in Dartmouth, N.S., almost 20 years ago.

“He came out, I guess, in a half-drunken rage and ended up punching me as many times in the head as he could,” said Matthew, who is now 34 and works in sales in Dartmouth. Global News has chosen not to reveal Matthew’s full name as he was a minor at the time of the assault.

“Then he had a friend who came over from around the corner and hit me with a crowbar,” Matthew said. “Then the two men stomped on my head and all over my body.”

The court documents related to Wortman’s arrest do not mention a second person. Global News called and emailed Halifax Regional Police for comment but has not yet received a response.

Matthew said he tried to defend himself and was thrown into a newspaper box as the assault ended and police officers arrived.

The denturist was charged with assault in October 2001, according to court documents.

.....

Details are slowly emerging about the shooter’s life that included a string of disputes with police, tenants and even family members, according to interviews and court records.

He was involved in an encounter in February with Halifax Regional Police over an unmarked cop car that was parked in the lot outside his clinic.

Wortman’s uncle filed a case against him in Nova Scotia Supreme Court over a property in Portapique [where the rampage started], N.S., after a dispute arose over financing, according to court records.


It's unclear whether he was allowed to have guns.

Reading that it seems he was going to snap at some point. Whether the lock down put him over the edge or gave him opportunity to act, don't know. Whether the lock down made the outcome worse, probably not. Most people were inside and he shot a random jogger along the way. He could have killed a lot more people if they were outside. It's a quiet rural area, not a lot there to stop him. Police did stop him before reaching Halifax.