SQL Server 2014 is now supported with ArcGIS 10.2.1 and 10.2.2
Pls refer to ArcGIS Help (10.2, 10.2.1, and 10.2.2) , which does indicate SQL Server 2014 under 10.2
SQL Server System Requirements
Since the SQL Server 2014 question has been answered, I will just point out the latest release of ArcGIS for Server is 10.3.
it looks that 10.3 still demand SQL Server 2012 or earlier (below).
My guess, that table you reference simply has outdated information.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.
SQL Server 2014 is now supported with ArcGIS 10.2.1 and 10.2.2