Workaround: instead of using the default alternating row color for the mentioned themes, use the override theme setting in the CellFormatting event: http://www.telerik.com/help/winforms/tpf-override-theme-settings-at-run-time.html
private void radGridView1_CellFormatting(object sender, CellFormattingEventArgs e)
{
    if (e.Row is GridViewDataRowInfo)
    {
        if (e.RowIndex % 2 == 0)
        {
            e.CellElement.SetThemeValueOverride(LightVisualElement.BackColorProperty, Color.Red, "");
            e.CellElement.SetThemeValueOverride(LightVisualElement.DrawFillProperty, true, "");
            e.CellElement.SetThemeValueOverride(LightVisualElement.GradientStyleProperty, GradientStyles.Solid, "");
        }
        else
        {
            e.CellElement.ResetThemeValueOverride(LightVisualElement.BackColorProperty, "");
            e.CellElement.ResetThemeValueOverride(LightVisualElement.DrawFillProperty, "");
            e.CellElement.ResetThemeValueOverride(LightVisualElement.GradientStyleProperty, ""); 
        }
    }
}