"Achter’s lawyers argued that allowing an emoji to act as a signature or acceptance for contracts would open the flood gates for cases interpreting the meaning of the images."
I totally agree with that sentiment.
When it comes down to it, is the thumbs up emoji really that different than a "yes," "X," or a signature? In the past people just gave their mark when agreeing to something and it doesn't appear that there were any standards as to what that mark would be. If someone hands you a contract and you write an 'X' on the signature line, how does that differ from an actual signature?
Letters and language are meant to convey meaning and it seems that meaning was conveyed here. Someone else also commented that this person had a history of using the emoji to agree to things which just lends further credence to my point.