Ah. Yet another update to that list.
I haven't figured out a way to get the list of actually valid build targets, so I have to keep a list of deprecated ones.
Open the OptimzationHandler.cs file and add the lines
(BuildTargetGroup)2, /* WebPlayer */
(BuildTargetGroup)20, /* PSM */
(BuildTargetGroup)22, /* SamsungTV */
(BuildTargetGroup)24, /* WiiU */
to the definition of the deprecatedBuildTargets array. Let me know if that works.