The EAA in the USA has much less oversight of projects than the LAA or BMAA have in the UK.
Experimental aircraft in the USA can be much larger and more powerful (like this one) than would be permitted for homebuilts in the UK.
I know having worked in the UK, that we have a lot of trouble ensuring adequate quality control is in place with kit manufacturers. The USA doesn't generally investigate it and put it to trust.
None of which tells us what happened for this aircraft, and it may be completely unrelated to the aircraft quality.
G