The TSB report shared in link from Albatross is sure worth reading to try to understand what happened. This wasn't a case of fuselage reacting to torque from the driven rotor, rather fuselage rotated right (clockwise seen from above). An extract from report:
"When the engine was started the 3rd time, the right anti-torque pedal was fully forward. Then, with the pilot’s feet either lightly resting on the bottom of the anti-torque pedals or not on them at all, once engine power was increased to flight idle a significant yaw force was exerted on the helicopter".
I am no pilot, but shouldn't the pilot have felt with his feet that the pedals were not roughly aligned with one another on the third start?
This accident occurred 6 May 2023. The report at 1.18.3 mentions a subsequently reported very similar Canadian case on 28 Sept 2025 where another Squirrel likewise had a right yaw during ground running when pilot didn't have his feet on the pedals. Fortunately no injuries in that case, just some damage to the helicopter.