Board Thread:Speculation House/@comment-24457155-20161104075653/@comment-26397825-20161104080132

Her eyes very specifically turned white, not silver. Silver eyes are their own special colour, and there are multiple people with grey or 'white' eyes (such as Mercury and Neo) who are not Silver Eyed Warriors.

Plus, the out of universe explanation is that Neo wasn't even a concept until Volume 2, whereas Summer has been around much longer. Neo was created because Monty felt like Roman needed a sidekick, and her design is based off a genderbend Roman Torchwick cosplay.