While some events are pretty laid back, it looks like the registration for this event cost ~$2000, which is a pretty penny. My gut instinct would be to check with the event organizers first before trying to bring a +1, but I think the OP assumed that because he was able to negotiate with the travel coordinators for two one way tickets, one for his wife (instead of one round trip ticket), he probably assumed that this was implicit consent for his wife to tag along at the conference. Seems like a big mis-understanding that was confounded by poor treatment from security staff (and before we start ragging on the security staff, it is worth mentioning that event security tends to be a thankless, miserable job. Crappy wages and hours, and depending on the event, you spend most of your time dealing with people who treat you like shit.)
These events may charge $2000 a head, but it doesn't cost them $2000, or even $5, to let a +1 watch your talk.
It looks like the OP is an established consultant/teacher, so he probably only goes to conferences that invite him to speak (and my guess is, from what I have heard about you tptacek, that you are in the same boat), so he may be unfamiliar with the practice. But for us peons, with little to no name recognition, conference papers and talks can be a big resume booster, so it's not out of the question to pay-to-speak (you still have to go through the proposal process though). In my old industry, this was standard practice, and because almost everyone had their conference registration and travel paid for by their employer, it wasn't a huge deal.
At TechEd, Microsoft picks you, guides your session abstract wording, reviews and changes your slides, specifies your clothing, tells you when to show up for booth duty at the Microsoft booth, and pays you for it. You're basically a community mouthpiece for Microsoft. This is very much a vendor event.
Lest anyone think I'm being judgmental I personally might have shown up about 0 minutes before I had to talk and behaved exactly like he did.