That's a problem with how the media presents stories though: after the bombing, the guy was the "Homeless Hero" who prompted widespread support (and virtue-signalling, but that's another thing altogether) when a bit of research by a professional journalist would probably have suggested that the story not be run. Now, we know that the person was dishonest and was not the hero he claimed (or was claimed) to be, so he's now branded scum and faces calls that he be stoned to death in St. Peter's Square.
The reality is that he was and is obviously a man with a long list of issues, and perhaps coming unstuck in such a high-profile way will be a wake-up call. That's not to say he shouldn't be punished- but the emotions surrounding the tragic events in Manchester shouldn't overly influence his sentence because that's not what the courts are for. See also the Riots of a few years ago: kids were being sentenced for silly tweets as if they'd been feeding pins to the Queen's swans! Trial by media is rarely good justice.