This change gives people who committed plagiarism and got a permanent ban, a third chance, not a second chance.
Not really. That would imply being pardoned and repeating the offense. The possibility of appealing a ban from the "good for the forum as a whole" perspective did indeed already exist - IIRC signature bans were added in support of this back then.
This thread acknowledges the possibility of an appeal and also provides a more clear guideline, all wrapped in a Holiday spirit fashion.