He didn't ask for free tickets, just admission to his talk.

It's a common courtesy and necessary. You need to be able to take pictures on your own to safely be able to use those pictures in your own marketing or other material.

I've never spoken at a major conference, but the folks whom I've worked with who have at a corporate/organization always bring an assistant or friend to take pictures to memorialize the appearance. I've been the assistant role a couple of times early in my career -- 2/3 times I was given a "exhibitors hall" or "sponsored session pass" gratis.