They already know that everyone editing old posts is doing it to screw with them.

As others pointed out they will ignore all edits. Especially edits made after 1 day.

Losing the rare grammatical fixes or additional info that was changed weeks later doesn’t matter to them. Keeping the version last changed within 1 day of first edit gives them everything they need.

The only way to mess with reddit would require posting wrong information with a community of like minded redittors that would up vote the bad information.