Unless the UserControl has its own logic to resize the columns, the width of the UserControl will be bound to the width of its columns. I would try implementing the WinFormsHost inside a ScrollViewer, if that will be an acceptable layout.
<ScrollViewer Grid.Row="1"
Grid.Column="0">
<WindowsFormsHost>
<winforms:ServicesUserControl x:Name="servicesUserControl"
UserCanEditRevenue="True"
BorderStyle="Fixed3D" />
</WindowsFormsHost>
</ScrollViewer>