Should I request a new winner?

yeap do what you feel what is right

With games revoked by steam, do you mean games that are no longer being sold on steam? That is still allowed, nothing shady about that (some of us have leftover keys for old games no longer sold on steam).

You won't be granted a re-roll unless the person has actually broken some site rules (not activated wins being the prime one), and then only if the person has not already been punished that particular rules transgression in the past.

If the guy has broken some rules you can ask for the reroll, I can confirm that you can and s/he will be suspended. If that person "pay his debt" in th past maybe you can't ask for a reroll.

that's probably not a valid reason to reroll, but you could try.
worst case you will have to wait a while to get a reply from support and have the reroll denied. and they will also hate you for wasting their time :3

imo this guy shouldnt be on steamgifts. But still, I dont think its not enough reason to ask for reroll. It will probably be denied.

report, and see what happens.
If you're denied, give the game and blacklist

From what the FAQ says, the only "punishment" that people who create fake giveaways get is a deletion of said giveaways. I doubt you can reroll but i guess it's worth the try.

I'm on a different situation but i have a doubt regarding rerolling as well. I hope you don't mind if i ask it here instead of creating a new thread.
If you add the key when you create the giveaway, when it ends does the key show up on their won list automatically or do you need to press the "sent" option? Winner was last seen online 3 minutes before the giveaway ended so I deleted it just in case.

It can't hurt to submit a re-roll request and explain the situation.
The worst they'll do is deny it and call you names, publicly flog you, and steal a kidney