Being gender neutral when not knowing the character's gender for sure was the proper choice. Making assumptions can bite translators in the ass.
One of the biggest I remember was the original translators of Denki-gai no Honya-san decided to not use honorifics and as a result assumed Hiotan's nickname was Hio, removing the tan because they thought it was an honorific. A couple of volumes later we found out that the whole thing was her nickname, so all those chapters using Hio were wrong and never fixed.