Well, at this point, that's what he himself has said, since it was a guilty plea. Presumably he had to admit not just his actions but his intent / malice.
While I tend to agree with you that he likely did something malicious, a guilty plea in this day and age doesn't really tell you that.
He may have been taking a plea bargain out of fear of much worse?
The problem with pleading guilty, is that then everyone thinks that you're guilty.
While he might have taken a plea to avoid a more serious charge, last time I checked you still have to be guilty of whatever lesser crime you're pleading to, as well. You're not allowed to make up a lesser crime in the name of bargaining down.