If the noise was the same as the 7D2, there is no good reason to drop the ISO... because that's just pixel peeping noise levels. When your 50MP image is downsized for a print, you'll have much less noise than the 7D2 shooting the same image, or if your printer can handle that resolution, the noise will be so fine as to not matter.

I don't buy it that FF users can't tolerate the 7D2's level of noise because Bryan's noise comparison charts, on the 7D2 review, shows very similar levels of noise on both... perhaps a 1 stop difference. 7D2@ISO 6400 is very similar to 5D3@ISO 12800, but 7D2 is clearly cleaner at @3200, so even at the pixel level a 2 stop drop isn't needed. Once you downsize the image to the same resolution or make a print, I'm not sure you even needed the pixel-level equivalent to 5D3 one stop drop.

Perhaps this new sensor does have more heat-induced noise issues than 7D2.