According to the Art of TFA book, they considered making Snoke female. Palpatine repeatedly referred to Plagueis using male pronouns.
As I said before I don’t think Snoke is actually Plagueis, but if that were the case it could be an element of his character that was conceived later. It could even, hypothetically, be something Rian Johnson conceived that was then infused into TFA. We just don’t know at this point, not just whether Snoke is Plagueis but Snoke’s backstory at all. TFA is vague enough on it that whatever preconception as to his origins when making that film could be changed when making the next.