It's not just a Conservative thing to deal with right wing dictators. I do recall Chretien having a cozy relationship with Suharto of Indonesia in the early to mid 1990's. Both Liberal and Conservative governments will deal with both left and right leaning authoritarian regimes when they deem it in the national interest to do so. However, it is a different matter all together to legitimize a dictator  and his/her regime  in  eulogy.  
A private not from J.T. to the Castro family done in private to give a node to the personal relationship is completely understandable. But the official word from the PMO and the government of Canada should have reflected Canadian values..