If 100% of their engineers are women then yes they still have a problem. If it's a sign that they have a more even balance then it's a good thing because they're not wasting/ignoring 50% of the potential pool of people, and because diversity of backgrounds leads to better decision making and more innovation[1] which presumably as a tech company is a desirable outcome.

[1] See references to papers in this blog posting: http://stumblingandmumbling.typepad.com/stumbling_and_mumbli... and also https://hbr.org/2013/12/how-diversity-can-drive-innovation