Hey. You can't add custom rules to the giveaway, it's against the rules:

You cannot ask users to perform any special action in order for their entry to be considered valid, such as liking a Facebook page, or following a Twitter account.

You may ask winner to allow you delete this giveaway (and most people will agree, if you ask, community here is friendly mostly), but in no circumstances you can require it. And of course you can't forbid someone to enter giveaway if they are not agree with your custom rules.