The PM has nothing to apologize for. Messages from other world leaders are in line with Trudeau's comments (Kofi Annan, Ban Ki-moon, Jimmy Carter, Pope Francis, John Kerry, Obama etc).  
Fidel did some bad things. So did George Bush. No, we don't like dictators, but our methods of dealing with dictators, hitherto, have not worked; #Iraq, #Libya.We need to rethink our approach. The US harsh rhetoric and embargo on Cuba was an abysmal failure. They did not achieve the desired aim of overthrowing Fidel. Rather, they hardened Castro and collectively punished the Cuban people. 
Fast forward to Myanmar. Quiet diplomacy (not holier than thou relinquish power or die ultimatums) finally convinced the dictators to ease off after decades of dictatorship. Myanmar is not perfect yet, but lessons needs to be learned. Carrots, mixed with gentle sticks go a long way. The PM's quiet diplomacy is more effective than the conventional  pontification from the likes of Clifford Owin.