Comment by QuantumNomad_

And in particular, people might lurk for a long time without an account until one day a thread makes them want to comment so much that they go ahead and create an account to comment.

Although, the username they picked in this case does seem a bit specific to the topic of the single comment they wrote. So it remains to be seen if this particular case was a throwaway account only used once, or if they will keep it.