When setting IsEnabled to False, there is no change in the component.
Use the following code, observe that the RadSegmentedControl is still enabled at runtime.
<telerikInput:RadSegmentedControl x:Name="segmentControlText"
BackgroundColor="AliceBlue"
IsEnabled="False"
VerticalOptions="Start">
<telerikInput:RadSegmentedControl.ItemsSource>
<x:Array Type="{x:Type x:String}">
<x:String>Popular</x:String>
<x:String>Library</x:String>
<x:String>Playlists</x:String>
<x:String>Friends</x:String>
</x:Array>
</telerikInput:RadSegmentedControl.ItemsSource>
</telerikInput:RadSegmentedControl>