Because that's not independent verification that the device tested actually _is_ a solid state battery. Just that whatever was tested had certain charging characteristics.
Tbh the exciting part isn’t so much the composition but whether it can actually meet the claimed performance. It could be made of wet gym socks for all I care if it can do 100k charge cycles at 90degC with comparable energy density and specific power to LiFePO.
But that’s the point I’m making. You’re taking the claims that Donut Labs is making about it being a new type of battery at face value. Having someone verify charging characteristics isn’t that helpful without simultaneously verifying that the battery actually is what they’re claiming.