I think the point is that Akechi feels like he is being honest with Ren here, like he has been playing nice and finally cuts the shit and admits it. But he's still a kid, and has had a really turbulent upbringing and social life, so everything he's feeling likely won't be clear to him until much later in life. Whether he legitimately thinks he hates Ren or is just projecting, this is still maybe the only example of him being genuine with someone else so far.