Add a new property AllowSelection/EnableSelection in order to control whether the use can select a cell/row.

Workaround:

Private Sub RadForm1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
    Me.ProductsTableAdapter.Fill(Me.NwindDataSet.Products)
     
    Me.RadGridView1.CurrentRow = Nothing
    AddHandler Me.RadGridView1.SelectionChanging, AddressOf Grid_SelectionChanging
    AddHandler Me.RadGridView1.CurrentRowChanging, AddressOf Grid_CurrentRowChanging
End Sub
 
Private Sub Grid_SelectionChanging(sender As Object, e As Telerik.WinControls.UI.GridViewSelectionCancelEventArgs)
    e.Cancel = True
End Sub
 
Private Sub Grid_CurrentRowChanging(sender As Object, e As Telerik.WinControls.UI.CurrentRowChangingEventArgs)
    e.Cancel = True
End Sub