Notice how he doesn't mention Subaru at the end. Each seat needs to be tested specifically for this application and no Subaru's have been tested (it's mostly Euro cars).
Is a four point harness "safe" in a rollover?
That depends on a lot of variables, but one of the biggest is the car itself. Older cars (pre 2010...at least) did extremely poor in crash tests that focused on A-pillar pressure. NHTSA started to include this rollover type test in the last 5-10 years and a lot vehicles tested very poorly. Since then, manufactures have made a much better effort in addressing this weak point.
So, if you combine an older chassis that tested poorly with a fixed back seat and a 4pt harness, I'd say that's a recipe for disaster......roof caves in rollover accident, no give in the seat and a driver that is very securely fastened to that seat. Doesn't sound too enticing.
The only place I would ever consider a 4pt is autocross. I'd NEVER consider one on track.....especially with a fixed back seat.
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