It's a big, shiny, demanding ego. It's all typical of Bill. His ranting and raving is just silliness.
Does Takei even realize he's the pot to Shatner's kettle? Yeah, Bill's the one with the biggest ego here.
Could you imagine the actor who had tenth billing on Forrest Gump complaining that the movie spent too much time focused on Tom Hanks' Forrest Gump character?