"Although I still believe that the you of ten years ago would never hurt Chris, that's not what the current evidence points to. In fact, your future self appears to be the only one that might have ended up killing him." Even explained.
Mai's mind was twirling at the thought, of course she knew how much a person could change in ten years. Future Simon was living proof of how much could change in one decade. Still, she was convinced that it couldn't be her future self.
It would be too crazy for Future Mai to have appealed to her younger self to get out of trouble. Heck, in that case she could have just given Mai false information to sabotage the past so the two of them would never get together in the first place.