Button with style defined in XML works; not same if style set in code

Question

I'm trying to add a style to a button in Xamarin Android from code, because the buttons will be generated dynamically and need to change colors based on other system events.

Using the code shown here, I expect that the two rows, one rendered from XML and the other from code, will look exactly alike. Instead, I see that the style ButtonDefaultTheme is only applied to the first row.

I know setting the style from code is possible based on this answer and this one. I think I could accomplish what I need using a layout inflater as in this answer, but I'm very curious why the code I have won't work.

public class MainActivity : Activity
{
    protected override void OnCreate(Bundle bundle)
    {
        base.OnCreate(bundle);
        SetContentView (Resource.Layout.Main);

        LinearLayout roomButtonLayout = FindViewById<LinearLayout>(Resource.Id.roomButtonLayout);
        LinearLayout roomInfo = new LinearLayout(this)
        {
            Orientation = Orientation.Horizontal,
            LayoutParameters = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MatchParent, LinearLayout.LayoutParams.MatchParent, 1f)
        };
        roomInfo.SetGravity(GravityFlags.CenterVertical);
        roomInfo.SetPadding(20, 10, 0, 10);

        TextView roomNameDisplay = new TextView(this)
        {
            Gravity = GravityFlags.Left,
            TextSize = 20, // defaults to scaled pixels
            Text = "Room 100",
            LayoutParameters = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.WrapContent, LinearLayout.LayoutParams.WrapContent, 1f)
        };

        roomInfo.AddView(roomNameDisplay);

        Button button2 = new Button(new ContextThemeWrapper(this, Resource.Style.ButtonDefaultTheme), null, 0)
        {
            Text = "View2"
        };

        roomInfo.AddView(button2);

        roomButtonLayout.AddView(roomInfo);
    }  
}

In Main.axml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:gravity="center_horizontal"
    android:layout_width="match_parent"
    android:paddingLeft="10dp"
    android:paddingRight="10dp"
    android:layout_height="wrap_content"
    android:id="@+id/roomButtonLayout">
    <LinearLayout
        android:orientation="horizontal"
        android:gravity="center_vertical"
        android:paddingLeft="20dp"
        android:paddingRight="0dp"
        android:paddingTop="10dp"
        android:paddingBottom="10dp"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_weight="1">
        <TextView
            android:gravity="left"
            android:textSize="20sp"
            android:text="Room 100"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1" />
        <Button
            android:text="View1"
            style="@style/ButtonDefaultTheme" />
      </LinearLayout>
  </LinearLayout>

In styles.xml

<?xml version="1.0" encoding="utf-8" ?>
<resources>
  <style name="ButtonDefaultTheme" parent="android:style/Widget.Holo.Button">
    <item name="android:paddingBottom">0dp</item>
    <item name="android:paddingTop">0dp</item>
    <item name="android:paddingLeft">10dp</item>
    <item name="android:paddingRight">10dp</item>
    <item name="android:layout_width">wrap_content</item>
    <item name="android:layout_height">wrap_content</item>
    <item name="android:layout_weight">1</item>
    <item name="android:minWidth">100dp</item>
  </style>
</resources>

Result:

• Minimum API level needed: 19

• Compiling using: 21 in actual app, 23 in test app. Same visual results in both.