There weren't only Malaysian citizens on this flight, there were people from all over the world and thus other countries should be able to help find their own citizens. The country should be welcoming all of the help that it could get. Up until now we still didn't know where the plane might have landed or crashed so I think it was imperative that other countries aid in the search.
All countries should aid in the search for the missing Malaysian Airlines' flight due to the humanitarian nature of the project. If all countries pooled their manpower and technological resources, there would be a better chance of finding the missing airplane. Families of the flight victims could get answers as to what happened to their loved ones, and begin to heal.
If this is a case of piracy or mental illness in the pilot, airlines in every country could benefit from the knowledge, and perhaps stop this from happening again.
I believe any person or entity that wants to help in the search for the Malaysian Airline plane, should be allowed to help. Helping is what creates a community and I think searching for this plane could be a global community event. Why would we stop a certain group or certain set of people from attempting to help?
People should always help when a tragic situation happens. When did doing the right thing become so controversial? Besides, there were many people from different countries on that flight. We should want to know what happened, that way we can try to prevent these tragedies in the future. Every country has a stake in that.