However, that sentence "But the government of Iran probably could" made the preceding paragraphs appear to be a vehicle to deliver a meme (like a shaggy-dog story). The rest of the article could have been great, I just stopped reading.
The journalist could have made a neutral statement about what entities have the resources to crack a 768-bit key. But they or their editor chose not to.
Instead, everyone that reads the article will go away with the meme "Iran, if they wanted to, could crack 768-bit keys". Which is, by common definition, propaganda.
It might be unintentional, i.e. the journalist is riding a wave of popular opinion, which they should not do; or it might be an attempt to load the article with link bait.
I don't understand. That statement was part of a quote during the interview. A single, continuous quote. Do you consider reporting what someone said to be propaganda. Should the journalist have left out that part of the quote?