Apparently it won't be, since some people here seem to think stealing from its users is a commendable practice.
Seriously, how would you handle the case "someone sends an unconfirmed TX right before the bet ends, TX confirms after the bet has been decided" ?
Refund?
You want to discourage scammers, not have to guess every time whether the request is legitimate or not.
Just add a reasonable fee for this kind of refund, it is more than enough to keep scammers away. Charge, let's say, 5% of the amount received. There is also the case "someone sends a transaction not so right before the bet ends, TX confirms after the bet has been decided", refund at 5% fee, too, obviously.
I can't even start to understand why you think this is not the proper way, and stealing is the correct choice. MP really got a legion of fans.
The underlying theme of any MP-affiliated business is that the rules will be set up to protect that business's bitcoins at all costs, despite their user-unfriendliness. The unfortunate fact is that even though its very unlikely that OP was trying to scam, bitcoinland is full of people that can and do scam any service or person that has an exploitable weakness. The level of fraud among bitcoin users is tremendous, much higher than any other consumer financial environment. Hence, rules that seem reasonable based on real-world experience where perhaps 2% of transactions are attempted fraud leave bitcoin businesses too exposed, as this is an environment where perhaps 20-50% of transactions are attempted fraud.