@Ceili,
That argument is a rather tired old canard which has been around, and often repeated, for the past thirty uears at least. Apart from some NGOs such as the one that issued your cited piece no one takes it very seriously anymore.
The notion that the U.S. embargo has been either the cause or the excuse Castro used to rationalize his repression of Cubans over the past decades since it was enacted depends on the assumption that he wanted or believed he needed such an excuse or pretext. Many facts give the lie to that assertion.
There have always been critics of the U.S. posture on the Cold War standoff with the former Soviet Union. The sources for this were many and various including a fear of war and naive belief that the Soviets would outgrow their paranoia and revolutionary ambition; the wrongheaded belief that the U.S. was a neo colonial power, perhaps in the mode of the former British Empire; simple naive belief in Socialism; jealousy of U.S. power and self-interest; among many others. I believe these attitudes contributed to the endurance of this absurd argument. Indeed Castro was seen as a sympathetic character by many such folks, despite his oppression of his people and many human rights vilations in Cuba and other places, After the Bay of Pigs fiasco, Castro had good reason to fear U.S. interference. However after the missile crisis and the showdown with the USSR Castro was protected by the same nuclear deterrent that protected the major powers.
The fact is the embargo didn't deprive Castro of anything except perhaps credit from U.S. Banks. Conversely it did protect the United States from finding itself subsidizing Castro's efforts to spread his authoitarian revolution into Lattin America. Under Castro's rule Cuban agriculural and commercial industrial declined precipitously leaving them with very limited sources of hard currency cash from exports, and utterly dependent on subsidies from the USSR. They had no income with which to buy anything- as a direct result of their own foolish, repressive policies. When the USSR collapsed their situation worsened significantly. Many western nations, including Canada, expressed sympathy for Cuba, but none of them turned that into meaningful aid or subsidies for the Cuba with which they expressed such heartfelt sympathy.
Cuba is just 90 miles from the United States: it is a long way indeed from Canada.