Requesting a new Winner requirments ?

YES!
request new winner.
that's reason enough.
breaking rules multiple times.. ( regifting won games) etc..

I don't know if it's a valid reason to request a new winner... but it definitely should be.

Yes, definitely.

"A giveaway can be rerolled upon the gifter's request. Valid reroll reasons are:

Did not own base game for DLC
Leaked giveaway
Majority of bundle exists on account
No longer a group member
Previously won the game or already on account
Regifted or did not activate previous wins this month
Suspended or inappropriate behaviour
Unable to contact through Steam or email
Winner rejected gift
A reroll request is approved if at least one of those reasons can be applied to the winner of the giveaway."

I would say it's a very good reason for a re-roll.