It will be interesting to see the actual charge. The usual charges when people have been nasty online are either related to malicious communications or to stirring up hatred against a minority group (this was what Lucy Connolly was prosecuted for).
But the tweets about Widdicombe don't fall easily into either of those categories. It's hard to charge someone with malicious communications when the target is dead.
So I do wonder if the charge is something to do with Herbert knowing in advance about the way she died. It would be extraordinary if true.