If he is eating a good amount of hay, it should be OK that he doesn't chew on other things like wood -- My rabbit has no interest in chewing on things aside from hay, and he's been able to sustain his teeth well. He used to not be able to, in which case he had his teeth grinded down once per month, but once we worked together to get his hay consumption up, he's been doing great.
That being said, those teeth look long to me.. but I'm used to seeing a netherland dwarf's teeth, so those may be fine for a larger rabbit? If you are noticing teeth grinding and other discomfort signs, I would recommend seeing a rabbit vet and having him/her assess properly whether the teeth need to be grinded down.
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