Yes, the only relevant property is the use of a duress PIN. They could have simply stated that he erased his phone with a duress PIN.
But "GrapheneOS! Spain! Profiling Pixel users! Spain equates GrapheneOS to criminals!" sounds far more spectacular and will give more clicks/links. Sadly, it feeds the narrative that GrapheneOS is just for activists/criminals/whatever. An iPhone in BFU state would have been nearly as safe, but nobody makes these implications about iPhones because everybody has iPhones.
But "GrapheneOS! Spain! Profiling Pixel users! Spain equates GrapheneOS to criminals!" sounds far more spectacular and will give more clicks/links. Sadly, it feeds the narrative that GrapheneOS is just for activists/criminals/whatever. An iPhone in BFU state would have been nearly as safe, but nobody makes these implications about iPhones because everybody has iPhones.