If you don't want people to bet right before the bet ends, then simply reduce the potential winnings gradually right near the end.
This is already the case, which shows you still haven't read the FAQ.
Then why is there any worry about last-minute bidders "scamming" other people at all?
It's about betting after the result is known.
You really read nothing, did you? Perhaps do that before taking a side.
If the result of a bet becomes known prior to the bet deadline, then no further bets should be taken. People can be free to send more money in, but they would get exactly 0% of the winnings, only having their money refunded.
How is this a hard thing for people to figure out? I don't get it.