ContextMenu in Style setter

Question

Does anyone know why this would produce an XamlParseException "Cannot add content of type 'System.Windows.Controls.ContextMenu' to an object of type 'System.Object'":

<ItemsControl>
    <ItemsControl.ItemsPanel>
        <ItemsPanelTemplate>
            <Canvas ClipToBounds="True"/>
        </ItemsPanelTemplate>
    </ItemsControl.ItemsPanel>
    <ItemsControl.ItemContainerStyle>
        <Style TargetType="ContentPresenter">
            <Setter Property="ContextMenu">
                <Setter.Value>
                    <ContextMenu>
                        <MenuItem Header="Remove" />
                    </ContextMenu>
                </Setter.Value>
            </Setter>
        </Style>
    </ItemsControl.ItemContainerStyle>
</ItemsControl>

And the following works just fine?

<ItemsControl>
    <ItemsControl.Resources>
        <ContextMenu x:Key="NodeContextMenu">
            <MenuItem Header="Remove" />
        </ContextMenu>
    </ItemsControl.Resources>
    <ItemsControl.ItemsPanel>
        <ItemsPanelTemplate>
            <Canvas ClipToBounds="True"/>
        </ItemsPanelTemplate>
    </ItemsControl.ItemsPanel>
    <ItemsControl.ItemContainerStyle>
        <Style TargetType="ContentPresenter">
            <Setter Property="ContextMenu" Value="{StaticResource NodeContextMenu}" />
        </Style>
    </ItemsControl.ItemContainerStyle>
</ItemsControl>