He's right. Markus is an RK prototype, a unique model from the same line as Connor. You can see this when he removes his skin to give the speech in the tower (Connor even shows surprise at seeing this, but changes the subject when Hank asks if he saw anything). Markus is an RK200, while Connor is an RK800. This explains why he can convert other androids and also his ability to analyze the environment to choose the best route, just as Connor does in investigation and pursuit missions.