There would be too little contrast between two shades of Turquoise if he used it as the background.
Matthew, I'd suggest ignoring the negative reviews that were left just to spite the resource. The colors aren't bad, but you should really start looking at doing more with changing the actual layout of XenForo (Then the whiners can't really say anything to you). You also might look at http://kuler.adobe.com for inspiration for palettes, as you'll be able to create a balance of colors that'll allow more depth to your design.
It look nice
try be more careful with font colours,
you sure know what you're doing and got the experience , try coming up with something great a new spend much time in making something great that many users will use better than small pieces of work .