George is not the first former Star Trek actor to mention that Shatner had a huge ego and was unbearable to others,
My favorite was Walter Koenig on Coast to Coast AM a few years ago. I think George Noory was the host. George asked him how it was working with the cast and he said "Read between the lines", then talked about how wonderful everyone was, leaving Shatner out of the list. When George asked "What about Shatner?", Koenig replied "I said 'Read between the lines'".
Unbearable people with huge egos that annoy others rarely recognize that quality in themselves - only in others who do the same. Ironic, isn’t it?