Actually that’s the proper call you would expect. You could put a comma after Good night. What the flight member is saying is “Good Night” and this is Malaysian three seven zero that is saying “Good night”. Otherwise the controller would have no definitive method in determining who is speaking to him if there were multiple flights on frequency. In Vietnam sometimes I would have upwards of ten or more flights of fighters on frequency and I really needed to be sure who I was speaking with.
And yet his call all throughout on the transcript at Post 7 was consistently "This is MH370" not "Malasian 370".
Why would the sign off differ from earlier communication???
I reckon they dropped the callsign, is all
You are exactly correct.