So what happens then is that the first 221 cards I discard are my air cards until I only have 29 left. At this point I still have 279 total cards, and can stall for 9 rounds without ever winning. Not quite as bad as before, but still a huge problem. I personally think this is far worse than the occasional illegal deck.
Note that discard being 30 doesn't mean an autoloss for this strategy either. I just have to run a deck that has more than 30 cards. With a conversion of 12, a 36 card deck is optimal, because each round I discard 18 off element cards and 12 air pillars/pendulums, then I convert 12 pillars/pendulums and I'm right back to where I started.