"We intend to create well-formed Emoji proposals for the most requested Emojis," the EmojiRequest website states. "We understand the process well and think that these proposals will have a good chance of being approved. Unicode may also choose to take our request data into consideration while reviewing Emoji proposals. However, the final decision lies with Unicode and there is no guarantee the Emojis you request will be approved."
In other words, voting for new emoji characters via the app or its website is very much unofficial and has nothing to do with the Unicode Consortium. However, EmojiRequest said it can use the data from all the votes it receives to propose the characters to the Unicode Consortium, which could potentially speed up the process of making them a reality, and most importantly, getting them on your phone. With any luck, you'll have a shiny new "Sad Poop" emoji in no time.