Being a programmer myself. I can say,
Online and Offline has mainly to do with a computer connected or not connected to the internet. Here, the key is the internet. I can say, I am working on my laptop offline. That means, I am working on my laptop, but not using internet.
In your case:
someone pulled an article from a website once
That means, someone already saved that article on their laptop and now they have a copy for later perusal. Now, they can access it without any internet connection. So, yes, they can say
they got it offline because now they are refereeing to the copy of the original article.
Example from Oxford dictionary:
‘Additionally, it allowed salespeople to synchronize data on their laptops for offline access - a specific demand of the sales force.’
‘System administrators have historically relied on offline archiving for data backup and storage.’
But, yes, if they say that they originally got the copy of the article offline, then they are wrong. First, you have to access online article and save it, and later you can access that copy offline.