Sorry, the information you’re trying to give kinda gets lost in translation. It’s hard for me to understand what is going wrong here.
The code works as follows: on a save of the predictions, every game is checked against the current system time of the web server. So there is – in normal circumstances – no way a user can alter a score if the date & time of the match are after the closing date (if set in the admin), or the date & time are beyond the time thresshold (in seconds) before the game (the other option in the admin for the closing of the allowable prediction period).
Only times I have seen this gone wrong were with timezone problems (or daylight saving time). Can you do some tests with that? See if changing the time of a match 1 hour earlier or later (depending on the timezone you’re in) does any difference. If not, extract/add another hour.
Any findings from you will maybe help me reproduce this and, if it is a bug, fix it.