It’s not inconceivable that it was on those chat logs alone. In the us the jury instructions read something to the effect of “this is what beyond a reasonable doubt means. It is up to you to determine if the prosecution has met that burden and you choose to apply as much or little weight to any piece of evidence or testimony as you see fit”
The police testified that they had collected evidence from Kik that his username send the messages. Only he had access to that Kik account, ergo it is him. If that evidence is accepted as factually correct you are cooked. Case closed.
Courts are inherently bad at understanding that technology has bugs. Injustice is the norm.
Yes, the root cause is that computer systems are seen as reliable witnesses even when they involve fallible human beings, e.g. the person making the request in this case.