They could probably knock it down to a malicious communication charge but because magistrates in England have to vote guilty when they believe that the incident occurred a solicitor representing him can’t try to tug on their heartstrings to get a not guilty verdict like they could with a jury (who aren’t working and thus can’t be dismissed over seemingly wrong verdicts like a magistrate can).
If the evidence suggests he did it and the magistrates voted not guilty because they pitied him they could lose their jobs (although theoretically a guy in a care home could run an insanity argument ig he’s got mental health difficulties and such like).