It's not right. There are linguistic restrictions on gender-neutral, singular 'they'.[1] When the referent is known, it can't be used (i.e. it's not about 'patrick' and 'he' matching up, it's about 'they' not being usable with a known person).[2]

My favourite real-life example of it's usage is one in which we know that the gender is female, and we know it's singular:

"If a mother wants to use the nursing room, they can just key in the code in their pamphlet".

[1] https://www.reddit.com/r/linguistics/comments/3cgbyv/limitat... gives some good discussion

[2] I can't help but feel that these restrictions are related to nondefinite contexts for "(negative polarity items)[https://en.wikipedia.org/wiki/Polarity_item]", like 'no-one' and 'any', where you can't say e.g.

    *I ate any cake

but you can say:

    I didn't eat any cake

but you can also use it in questions:

    Did you eat any cake?

This seems related to usages like

    If someone comes, tell them to wait

vs

    *If John comes, tell them to wait.

It doesn't sound right because the username includes "patrick", which implies a "he". Singular "they" doesn't replace "he" or "she" when gender is known.

It sounds a bit more natural if you say "That user didn't read the article, so they were uninformed."

Why not? This is not new at all, I've used it whenever I'm not sure of the gender of a subject for as long as I can remember.

That would be awful, but is a misunderstanding. People say "they were" for the singular, just like "you were" (not "you was").