The attendees paid big money to attend this event, the Livestrong gala. So,it would stand to reason that they are his most diehard supporters.
Have a look at Armstrong's acceptance speech (below). It's been posted before, but here is the link again.
Note how carefully crafted Armstrong's speech is. It's purely a function of Armstrong's PR team to give the illusion of support. The large number of people standing behind Armstrong on stage gives the illusion of support, it is very difficult to be critical of someone when they stand with the innocent. Also, there are key individuals that are obviously planted PR attendees whose role is to create an illusion of support again. The guy, front and center behind Armstrong who starts clapping (shortly into the clip) when the crowd lulls early on which gets more people clapping. The people directly front of stage area that stand early on which causes others behind them to also stand making it look like the crowd gave a willing standing ovation. The fact that international guests, like earlier invitee from BBC - James Pearce, were ushered as far away from Armstrong as possible, shows how choreographed everything s by Armstrong's PR team. Oh BTW, the link is to a YouTube video first posted by another user. With all the Armstrong fans watching that video, check out the ratio of likes to unlikes on the video page. It's not good for Armstrong.
Armstrong's speech in its entirety. Approx 5 min..
http://m.youtube.com/#/watch?v=rOKBU_U9hHA&desktop_uri=%2Fwatch%3Fv%3DrOKBU_U9hHA