His point wasn't that an MTG bot should be easy to run, his point was that it shouldn't be any easier/cheaper to run server-side than client-side.

But to address your point, while that is true, Sparky itself plays with very basic decks, and plays even those very poorly. The goal of Sparky is to introduce players to the rules, not to be a competitive MtG agent; playing badly is intended. I wouldn't be surprised if Sparky's code is actually just a bunch of very simple heuristics (maximize your mana utilization this turn, attack with any creature that can trade evenly or better, etc).