1) There's no way Aki could know exactly what happened. He doesn't know the truth, so he can't possibly tell it. He wasn't there, he never saw it. He only saw they were going somewhere, but he didn't see what happened, there were no surveillance cameras that far out. He only has educated guesses and theories.
2) Makima understands this, and I don't think she cares at all whether Aki tells her "the truth." He gave a full report based on concrete information that he had, that's all she needs, as long as Power and Denji remain useful and amusing/interesting.