What makes it a valid point? I see nothing in the definition of either word that would definitively preclude "puzzle" as an appropriate label. Riddle is fine too, but no mutually exclusive.
You and the parent comment claim it's not a puzzle, it's a riddle, with the implication that's somehow unfair or deceptive in how the problem was framed.
That is a semantic hair splitting that dodges the problem & its answer. In real life problems you don't get to define away responsibility for problems put in front of you. And if thoroughly stating my case is "overractive", then I'm guilty, but I find it's generally better to over-support my argument than state claims without justification.
