My guess, that table you reference simply has outdated information. Do you have a link?
If you look at the ArcGIS for Desktop - Microsoft SQL Server database requirements for ArcGIS 10.3 web page, you will see that SQL Server 2014 is supported. I thought I came across a similar ArcGIS for Server page, but I can't find it now. Also, a GeoNet discussion (Microsoft SQL Server 2014 and ArcGIS 10.2.2) from this past November has an Esri staffer commenting that SQL Server 2014 support starts at ArcGIS 10.3.