I agree with you when you say "don't plagiarise".
You are a very interesting case from which users asked for reasons why you unbanned, then with sudden permanently banwave, global moderators had new rights to unban users and make signature ban as reduced alternative ban.
I'm not sure that you are the first user fortunately unbanned from perma-ban or not, but based on that topic, it seems you are the first one.
[TIPS] to avoid plagiarismThere's been no policy change. redsn0w wasn't permanently banned due to several factors which made me think that permabanning him would be a net negative for the forum. Nobody is banned strictly because of "the rules"; it's always handled case-by-case, but almost always, plagiarists deserve to be permabanned.
If you think that a ban should be ended, make your case in a new topic from a "good for the forum as a whole" perspective.