Well... Snakeskin really isn't a colour. But more to the point, patterns aren't defined or even mentioned. A Nerf gun has multiple colours in various patterns. Even "digital camo"... Is a Nerf gun "two tone"? Would an m4 painted to look like one be two tone?
I'd say so.
It states predominantly a bright colour, but doesn't go on to mention the other "49%" nor does it prohibit patterning, or combinations. It's only intention is a differentiation to real looking weapons... So I'd use any colour mentioned, or colour combination.
As a citizen, my job is to follow the law, not the law plus some other stuff not mentioned. It's against the law to steal... But selling someone a biro for £1, when they could get it for 70p is arguably stealing 30p. But that's not illegal.
It's not taking advantage, it's just not following rules that don't exist.
To be honest... It's down to an individuals choice, which they might have to ultimately defend in court. And by that, I mean the retailer and not the customer.