On Friday, Assistant Secretary of State for Western Hemisphere Affairs Arturo Valenzuela put an end to any speculation that other heads of state would be invited to El Salvador saying that this trip is for President Obama to meet with the people of El Salvador and its government officials.
|Obama and Funes in the Oval Office, March 2010, Enduring Relationship|
I think that it's wise to not invite Colom. As I've said before, this is an important meeting between the presidents of the US and El Salvador that doesn't need the baggage that other heads of state would bring.
However, I wouldn't be surprised if the reason that Colom is not invited is not so much because of him but because Funes and Obama also would have had to invite the other Central American heads of state. You can't just invite Colom, or Colom and Chinchilla. You'd also have to invite Porifirio Lobo and Daniel Ortega which I don't think is in anyone's interest. That, or spend the entire trip answering why they weren't invited.