I am sure there is some reasoning to their policy on this, and it makes sense in some repects, but I am not going to attempt to understand their reasoning here.
Ultimately if you said that and your not, then I doubt you have much chance of proving it to get the funds back.
May be worth ringing them and get wife to speak to them saying your not a compulsive gambler and she asked you to close account. And explain you only said that for X reason, and kindly request if they can change the reason for your account closure and give you your funds.....
I"ve only ever dealt with financial complaints before but if you put it like that they may be more reasonable, its probably more a case of "computer says no" due to the reason you gave for closure....
Anyway Good Luck, hope I havent caused any offence with my honest assessment!