The key point is that we support the Falkland islanders' right to self-determination. I would argue that what the Argentinians have said recently is far more like colonialism, as these people want to remain British and the Argentinians want them to do something else.The implication is that being coerced by a foreign power is the definition of colonialism. This is an idea forged in the American Revolution and maintained by the Irish throughout the 19th century (not to mention nationalist movements elsewhere in Europe). However, this ignores the older definition of a colony that goes back to the Greeks.
The Falklands is a British colony (i.e. a "plantation" of settlers) in the South Atlantic. The fact that the islanders wish to remain British doesn't stop it being a colony.
The problem is that "the colonies" came to mean something else (a third meaning) in the 19th century: the invasion and systematic commercial exploitation of foreign countries, which occured mainly in Africa and Asia.
The result is that we find it difficult to use the word "colony" in its original sense, hence such clumsy formulations as "British overseas territories."
Oddly, one of the few places the word "colony" is still used in its original sense is in Sci-Fi. Of course, if we ever set up a self-sustaining presence on another planet we may decide to call it a "Terran trans-space adminsitrative unit."