I think some of this is true, but it doesn't really excuse anything.
I mean, you're right about his age and pizza and hobbies. They turn a tech-news story ("Major malware attack stops") into a human-interest one ("Meet the man who saved the internet"), which plays way better for these papers. The general public, or at least their readership, probably does enjoy those details.
And I suspect they didn't exactly consider this 'doxxing'. It's a less invasive piece than a lot of what they run, and the information was available via public sources. The Sun in particular considers felony phone-tapping fair game, so this is almost chivalrous by their standards.
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But... none of that justifies a damn thing. The general public wants plenty of things that are harmful or illegal, and we don't accept "people wanted it" as a defense of those things. The Sun, as I mentioned, proved that point in spectacular fashion.
Even conceding that the information was available, this isn't something excused by decent journalistic ethics. Publishing nominally-positive personal accounts about people without any attempt to contact them or let them request redactions is pretty odd. Showing up at their friend's houses without notice or interview requests to the main player is bizarre and unwelcome. Offering real name and location info on someone who just interfered with a major criminal action is downright irresponsible - he made the info available in the past, but might have felt pretty differently after interfering with this attack. Using his Twitter photos (unembedded) is comparatively harmless, but it's also illegal!
So yeah, I see why there was a human-interest piece run here. But that doesn't actually justify how the thing was handled.