While all the commentors agree that violent homophobia needs to be fought, one commentor suggests that it ought to be from the inside:
"I still think that any effort to fight this must come from the inside. People in general don't like to be lectured by foreigners. If on the eve of the Proposition 8 battle the leader of France made a big speech condemning homophobia, how would the American electorate react?..."
One answer to zazu's question might be that only the bigots (both in America and Uganda) would react to being "lectured" by foreigners. The victims would likely be grateful, at least if our efforts brought real change. Of course, the bigots hold the power, so maybe it's more about pragmatics than principle.
Though other commentors recall the example of Nazi Germany and how it taught us that no nation can afford to be silent to another's internal oppression.