Why shouldn't Humanists be examined also?
That's not actually an answer to the question I asked.
Your OP linked to an article about 'religious leaders".
For no known reason that I can fathom you asked if [Andrew] Copson and [Terry] Sanderson were going to be part of the research, despite both being well known as being part of notably non-religious organisations.
Which to most people would in itself make their inclusion extremely odd but there we go: so are you.
Clearly you're unable to provide an answer as to why you would even mention them. That's OK: I just wish you had said.