No, that's not possible, because the tables concerned don't exist in a populated form until after the merge has completed. Instead, the code could be re-written to process every nth table. For example:
Code:
Sub MailMergeToDoc()
Application.ScreenUpdating = False
Dim t As Long, r As Long
ActiveDocument.MailMerge.Execute
With ActiveDocument
For t = 1 To .Tables.Count Step 2
With .Tables(t)
For r = .Rows.Count To 3 Step -1
With .Rows(r)
If Len(.Cells(2).Range.Text) = 2 Then .Delete
End With
Next
End With
Next
End With
Application.ScreenUpdating = False
End Sub
where the '1' indicates the table to start at, and the '2' indicates that every second table from the table to start at is to be processed. Thus, as coded, the 1st, 3rd, 5th, etc. tables would be processed.