Testing against the most common forms of colour deficiency shows that the contrast is good enough for the vital navigational elements of the site as for the content copy.
The very rare occurrence of actual complete colour blindness or monochromacy as experienced by about 0.005% percent of the population (see also this article by a colour blind designer)is demonstrated in the grey image and suggests users with this disability would have difficulties in seeing the different states of the navigational tabs although they would still be completely usable to them (contrast background to type is always strong enough).
Courtesy for this minority group and striving for as much accessibility as possible might make me consider using another element to show the state of navigation. As the colour scheme should be adhered to for Corporate Identity reasons I might also consider not using tabs as a visual element.
