Actually this is good because under the previous Labour government that kid could have sued the guy for assault. It happened. Thankfully the law was changed to allow people to use reasonable force in their own homes to defend themselves.
Not sure why you mentioned Labour, was it different under the previous tory gov?
dig a little deeper on the chap mentioned in the article, and he was cautioned for Level 1 which is:
Level one porn: Definition: Non-erotic and non-sexualised pictures of children playing in normal settings.