Although this person's message was distasteful, I'm can't quite see how it meets the criminal threshold. Publicly hoping that a deceased individual's death was "extremely painful", and hoping that she died screaming shackled to her bed (referencing the pregnant prisoner story) is disturbing, but as Ann Widdecome herself said:
"Nobody has the right to live their lives being protected from offence or from insults or from hurt feelings."
The posts were made before the manner of Widdecome's death was made known, which makes it... slightly less worse?
That said, if the individual's employers see fit, they should be free to dismiss them for gross misconduct for making statements that reflect poorly.
I'm wondering if the police found worse in this person's other messages, or their harddrive...