In some states they do if you are never caught and convicted! and criminal felonies are a bit of a jump from forum infractions. Just saying!
Felonies are federal crimes. A conviction or warrant does not expire regardless of the state as far as I understand. The statue of limitations running out is something else entirely.
As for felonies vs infractions.. You brought up real world crimes and punishments as an analogy in your post.. I was expanding upon your analogy.
In my opinion, a warning is like a forum misdemeanor and an infraction is like a forum felony.
If someone posted real-life threats to me I certainly would not consider it minor, nor would I want such actions to be "forgotton" over time. Such things are as serious as it gets on this video game forum and should not be dismissed... Just like a felony.