PS I apologize for the confusion over the booking issue. I guess I didn't technically have an etkt#. I wasn't 100% clear on the booking vs itinerary process in my previous post. I'm somewhat of a novice traveler and not an expert on all the airline rules. I figured it didn't really matter especially with Thai immigration being fairly lax with Western tourists. Also, in the world of instant online booking I could have easily gotten an etkt with a few clicks on my phone.
But I feel like it's somewhat beside the point, since I said I would show the gate agent proof of onward travel (i.e. etkt#, i was a few clicks away from buying), and he refused to even look at that or be persuaded by it. He said it wouldn't make a difference.