Why not? I think if you use it for about 4 rides, then you'll break even compared to renting a tandem, which is at least $50 for a few hours plus the hassle of renting, picking up and dropping off, etc.

I'm not surprised you found it satisfactory. You had the sense to adjust and tune it first, and lack of that is probably 80% of the problems associated with department store road bikes. (I'm not sure Walmart should sell "mountain bikes" if they can't be taken off a 3-foot ledge without bending a fork, but I can perfectly understand road bikes being acceptable for casual use.)

Enjoy your test rides!