Yeah, blue doesn’t seem to appear in the New Testament (Greek), but it’s in the Old (Hebrew) as “Tekhelet”[1] which can apply across different blue hues, from turquoise to violet.

[1]: https://en.wikipedia.org/wiki/Tekhelet

Without considering what word was _actually_ in the Bible and what its translation(s) are, that's not a very convincing debunking.