Totally fair because it's a little thing called Game Balance(TM). They got to play a 4th game in the week that didn't affect game shape and had a prize attached. That prize can't be too big.
For the record, the B3 in many ways only truly begins in the round of 32. That's when the prediction competition begins, that's when games begin to be played in neutral arenas, and that's when the prize money for each game ramps up to national tournament levels or above (The final in particular has a million dollar pot of gold attached).