I hope we are misinterpreting the interpretation. I can see that any connection could void the bonus, but I really think the intention was that you could not book from other cities and connect through MSP or DEN to get to LAX. For instance DFW-MSP-LAX or DFW-DTW-DEN-LAX.
I will have to wait and see as I have some LAX-MSP-LAX overnights "connecting" to LAX-DEN-LAX the same day. I am considering moving the lax-msp-lax to my Delta Sky Miles number so as to not void the promo on LAX-DEN, but if someone has it succesfully post I will leave it all WP.