ahh if V8's are your thing, go V8. If rotarys are your thing, Go Rotary, IF you prefer the good ol EJ series, then do that, either way, none of them are "cheap". maybe he had a wrx with a blown motor, and a 13b sitting in the garage.
The guys obviously not building the car to make other people happy. hes doing it for himself and has chosen something different. I mean who the hell cares if he puts a damn steam engine in it. its his car.
The other thing that should be mentioned is that they run a rotary shop. Rotary's are their thing.....clearly. so if you fix rotary's, have access to rotary's, know them inside and out...... why doesn't it make sense that they chose a rotary?