I'm not sure I follow what it is they're benchmarking (although I struggle reading text that has too many images so I may be confused as to what they're even doing).

I'd expect the bottleneck in a database index to be your disk or RAM access patterns. It seems very counterintuitive to see a real-world speed-up from SIMD if that is the case. The fact that they're seeing one in the benchmark would suggest maybe the benchmark isn't entirely capturing the right thing.