Either that, or said student had read Reflections on Trusting Trust. It was published in 1984. The 3B2's and Tymnet were current around then, and the authors bio indicates he's been programming long enough for the timeline to fit too. It's not that unlikely that someone, somewhere read the paper and decided to have some fun at some point.

The thing that makes me tend to agree with you is that he hasn't mentioned any "finally, years later, I found out where that guy got his idea" moment in it.