Good thoughts, but it shouldn't be able to access the domain/network (at least I hope not) as it is just accessing guest wireless. It's funny, there are millions of settings in the admin user's account for setting his or her settings and, of course, to set the guest. But, nowhere can I find a setting to set the home page or even make it open to anything other than "this is a guest browser." Which is probably the problem. It is telling the user, they can browse using the guest browser, but needs that home page to tell them that.
I will likely end up having to add a sticker to the Chromebook giving them the URL address plus /forms suffix to get them directly to the site. Given my anal-retentive and OCD personality, that will likely bother me for a week or so, then fade away.