@AlternativePerspective you've made a lot of assumptions there. And factually a lot of it is wrong.
"The fact he has previous convictions have absolutely no bearing on the actions he took yesterday."
It absolutely does to the people who have to assess his risk. Also his current conviction is not yet "previous". He still has to be regularly risk assessed due to this.
"It’s not like prison where the mob meters out vijilanti justice."
If you are involved with mobs and vigilantes then prison is often actually much safer than the streets of our cities.
"He was free, presumably considered rehabilitated, and clearly showed that fact in the course of helping to protect innocent bystanders."
No, he showed that he acted bravely but didn't necessarily think through the consequences of his actions. This could go in his favour or against him on any risk assessment. He was not free, he was on temporary licence with strict conditions. Think "day release". It's basically a test that does carry some risk for the prison service but needs to be done for resettlement purposes. He is absolutely not considered rehabilitated at this point. He's considered a lower risk than when he was first convicted and the release on temporary licence is part of his resettlement.
"If all of this is even true, where does it state that he was a murderer? Somewhere designed to take away from those who helped and create sympathy for the murderer perhaps?"
No, not from there. From the aunt of the teenage girl with SEN that he murdered. She has spoken out because she probably feels a bit sick inside that the country is calling him a "hero".