Well, to be honest I'd be a bit nervous about jumping up on stage to help him myself. As far as texting goes, I figure since most people were in a similar position, they figured Texting was better than going "OMG, OMG, OMGGGGG!!!!!!!111@@!!!".
To put things into perspective, let's say you've been trained like me in CPR but aren't currently up to date on certification (like a lot of people). Guy collapses and you enter the performance area to help. In doing so your risking that it isn't part of the show, or that your going to have some security type react badly to your prescence. Having worked security for shows before, typically if something similar to this happens we keep the audience back and wait for our own in-house EMTs to respond, even if someone says "I'm a doctor" (I mean can security prove this?). Not to mention the fact that assuming you do get there and do something, and even if your certified and it's up to date, the "good samaritan" law isn't exactly what it used to be. I mean if Mr. Science Guy isn't like his stage persona and is really hurt there, he might decide to come after you for your intervention. When it comes to good samaritans intervening in situations, either to stop violence (as the laws were orignally intented for, I believe they started with the Kitty Genevee case) or to try and help medically, you risk getting slammed civilly in a lot of places even where your protected from criminal charges. The protections have simply put been eroded over time by too many exceptions with people being able to sue "good samaritans" anyway, precedent being a major killer of legal intentions in the USA.
I guess this is unusually un-cynical of me on some ways since I'm defending these guys, but I'll say that before you cast stones at them for texting/doing nothing, ask yourself what they really could have done, or what you could have done if you were there. It's nice to say "well I would have run up there to help" but I think we all know we probably couldn't have. Even someone ike me who has had some training and might be able to do something in a case where nobody better equipped was at hand wouldn't be enthusiastic about doing so because I don't want to get arrested or sued (I was pretty much taught enough to hopefully keep someone alive in a desperate situation/emergency until an actual EMT could get there).