It's as Storm Machine says. Essentially, there's no rule against editing after submission, but the judges will read your piece when they read your piece, so after the submission deadline, there are no guarantees which version they'll read.

This is strictly a logistical rule. The log accepts any submission that's posted to the log prior to the deadline. It doesn't know how to read when the piece was last edited, and we're not asking the judges to check the last edited dates, either, because they have a lot of entries to read.

Cheers,
Michelle