Thinking has moved on since this came up. Even words like "significant" are still too flexible, now, a well written term has to be specific, perhaps taking the form "no bet greater than xx% of your starting balance may be wagered......."
The casino rep also managed to shoot themselves in the foot (I didn't spot it before). They said that the bet was "within the limits they had set". So the casino had specifically set a maximum allowable bet within the software, so surely this limit itself becomes a "term and condition", and if the player is able to select and bet $xxx, then the implication is that the terms allow it.
While it was not helpful to threaten the DDos attack, the casino THEMSELVES resorts to the same kind of tactic with that total BULLSHIT term that THREATENS the player with having their information handed over to Playtech for their "bonus abuser database" (which only exists in magic fairy land it seems

), which will ENSURE the player will never see another Playtech bonus again.
If C1C didn't want players betting $100 on Penalty Shootout, they shouldn't have SET the limit as high as $100.
When we have the abundant SPAM for these bonuses, the casino could be accused of running an unfair "honeytrap" scheme, where players are lured in by offers they cannot miss (unless they don't use email), and the casino can ENSURE they make a profit by weeding out enough winners to balance the books. Subjective terms are great for this, they can move the definitions around depending on how good their "hold" has been that month.
I consider nearly ALL Playtech casinos rogue. Since this incident, we have seen two MAJOR incidents, BOTH involving Playtech casinos, BOTH who received a progressive payout IN FULL from Playtech, and in BOTH cases some of the money "fell off the shovel" in transit to the player. This kind of thing goes beyond rogue, it is worthy of a criminal investigation since the money has ended up in the pockets of people who were not entitled to it.
NO "regulator" has stepped in to slap down the two casinos involved (one escaped by being sold on, but leaving it's liabilities behind), Playtech seem to have washed their hands of the whole thing, and this makes me feel that Playtech casinos are pretty dangerous places to play. Only the limited number of accredited Playtech casinos can be trusted, but I still can't bring myself to play at one of them.
C1C should define what they consider to be too large a wager, it is NOT "rocket science" to come up with a specific percentage, leaving the player knowing EXACTLY what bets are permitted, and which are not.