I think you mean possible rather than plausible? But otherwise I would say you're right, it's an exercise for personal amusement. But I think as you can see from elsewhere even in this thread, people slip into this mode of half-joking where they might as well be describing their ideas for Deus Ex fan missions, and the dividing line between serious engagement with evidence and make believe is breaking down.

I would argue that play is a highly valuable intellectual activity. Speculating for one’s amusement falls into that category and is therefore not worthless. A lot of great ideas come from playing around with strange ideas that aren’t obviously useful.