Board Thread:General Discussion/@comment-3304884-20151202081939/@comment-1504072-20151202102821

Although an interesting theory, it's rather speculative. The real reason why Raiden was called "Snake" is because he represents the player having taken the role of Solid Snake in previous games/VR missions/Tanker Chapter.

Minor nitpick, but a solidus isn't a gas, it represents a point between solid and liquid states.