In fact, as long as the malware is just doing deletes, you can just merge the two "timelines" by restoring the snapshot and then replaying all the edits but ignoring the deletes. Lost deletes really aren't much of a problem!

That doesn't really matter though against an attack that takes some time to spread. If the attack was active for let's say, 6 hours, then 43,000 legitimate edits happened in between the last "clean" snapshot and the discovery of the attack. If you just revert to the last clean snapshot you lose those legitimate edits.