Actually, it seems like a case of automated/formulaic calculations without the benefit of a human eye looking at the data. The D3100 read noise plot has no data point at ISO 3200, which was treated as 0.0 instead of being properly flagged as n.d. There's also a missing data point for ISO 3200 DR, which was assigned a DR of 25 stops in the table, another clear impossibility.
I have respect for most of DxO's methods (generally, and with the caveat that you have to understand what they measure, what they don't measure, and where the black boxes are so you can ignore meaningless values like the 'sensor score'). I also have respect for people who re-analyze others' published data. But I lack respect for those who report data that have obviously not been QC'd, which is immediately apparent from the read noise = 0.0 and the DR = 25 stops.
Since DxOMark does have data for the D3100 at ISO 3200 for both ISO Sensitivity and Full SNR curves, which Sensorgen draws upon for their source data, it seems that the problem is with Sensorgen's reanalysis, and not the original DxO data.
It is not necessary to attempt to reproduce someone else's results to invalidate those results in cases where the results are clearly not credible - and 0.0 noise with 25 stops of DR is simply not credible, any more than pennies and bowling balls defying gravity.