It really doesn't, but as you said that you have made some bets and it never happened to you, they should change something in ToS, it is confusing and just because it is part of ToS, site could force player to place large bet.
Ambiguous wording in contracts means that you are going to run into some problems. That is why they always make a big fuss out of the whole "You" and "We" pronoun game because any non-specificity can result in a legal loophole... for you or for we. 
They can just selective scam anyone with the help of this rule. Even I don't think it's mandatory to wager 1/2 of the deposit amount at a single bet to be able to withdraw your own money from the site. This sounds shady as hell in itself and can make it easy for the casino to earn money by selectively enforcing this type of rules and making it less fair for the players.
FortuneJack should comment on this 8.1.2 rule and clarify it's usecase or how is it relevant atleast.