Now, the beautiful thing about brain plasticity and speech language pathology services is that there is no age restriction! When I was in graduate school, it was drilled into our heads "there is no known cause nor cure for stuttering." What we have found in research is that some individuals have been found to be more fluent when working with auditory feedback or singing. There is definitely something he can do. I encourage you and your husband to find a Board Certified in Fluency Speech Language Pathologist in your area and get an evaluation and initiate some services. Being a great communicator is not necessarily about being 100% fluent; whom among us really is? I have had a few fillers and interjections (i.e., uh, er, etc.) myself in the midst of conversation! So, he can work on both presenting himself as a strong communicator as well as techniques to smooth the "bumpy" speech that may occur during higher verbal demand situations.
I pray that this was helpful!