Well, I don't think it should be allowed because it basically defeats the purpose of a lottery, but, as Matt points out in his article, I think a better way to prevent it is to make it easier.

If it becomes super easy to purchase millions of lottery tickets, then any arbitrageur would likely be dissuaded because the risk of someone else doing it (and having to share the winnings) go up by a ton. You could still have collusion, but that should be enforceable by laws against collusion I'd hope.

It this case there were rules to prevent arbitrage that were basically just not enforced by the lottery commission, and that's really the only reason this was possible.