(Does he travel from the tub to a warm area?)
They can often be coaxed into friendly relationships with their caregivers. It goes beyond merely tame, they can become socialized. I've heard of iguanas who run and hide behind their owners' feet when the doorbell rings.
If you work with your guy, he is likely to become much friendlier. This is a big article, but it's worth it to scroll down to Socialization (or Taming and Socializing). You might be amazed at what is possible, even with older ones:
He might feel cold and dry in your comfort zone, which will drive him to a more comfortable area. If you make a warm area in the space where you hang out, he may be willing to stay near you. That way he can learn your normal behaviors so your presence doesn't stress him anymore.
I know, too much information.