Molecular Orbital Diagram of NO

When we draw the molecular orbital diagram for molecules
  
 For those that have less than or equal to 14 electrons we use the order "σ1s σ∗1s σ2s σ∗2s π2px,π2py σ2pz π∗2px,π∗2py σ∗2pz"
  
and for molecules that have electrons from 15 to 20 have the order "σ1s σ∗1s σ2s σ∗2s σ2pz π2px,π2py π∗2px,π∗2py σ∗2pz".
  
Now when we consider the case of NO or nitrogen monoxide the number of total electrons is 7+8=15 so by the above stated logic we should use the second order but from all the sources I have gone through all of them have used the first order as shown below  

[![Molecular orbital diagram of NO](https://i.stack.imgur.com/3PWJg.png)](https://i.stack.imgur.com/3PWJg.png)


  
 Why is this?


