You read wrong or they edited, they are calling it m-ATX, which is correct. It is clearly not an ITX board.
Also interesting to note, the ITX Strix has 2 m.2 slots, one on the back and the one on the front. The one on the front though is sitting right on top of the PCH. They claim the heatsink works for both the PCH and the m.2 but that it keeps the m.2 thermally isolated from the PCH. Not sure how exactly that would work, but I have a feeling that the drive might get pretty hot on the front.
If this is true, I may upgrade... 2x m.2 is what I've been waiting for. a Fast NVME like the Samsung as primary (256-512) and then a 1tb 600P intel as storage. No sata power/data cables would be AMAZING. I HATE sata cables and extra cables from PSU that I dont require... Means 8 pin, 24, and 1x pcie 8 pin for my 1070. So clean.