The article points out one of the "Well, duh" things that I noticed when people got paranoid about AIM privacy -- namely, there's so very much going through that it would be horrendously wasteful of disk space and processing power to even think about monitoring or logging even a fraction of it. "Hundreds of gigabytes a day", evidently. I can see that -- I have extensive chats with friends, and we can get 20k text exchanged in 20 minutes no problem. I type faster than some people can even read.
Yes, it would be pretty simple to do keyword searches on IMs and see if there's anything worth listening to, from a security standpoint. And yes, that could be kind of creepy. But also keep in mind that if your e-mail provider is spam-filtering your e-mail, they're shuffling through your e-mail in a very similar way, which is also kind of creepy. It's for, after all, your own protection.
I have a somewhat relaxed view about those little personal details that I'd absolutely die if anyone else other than people I trusted found out about. I do not honestly give a flying fuck at the moon if some security geek over at AOL knows that ICQ User #55527386 has such-and-such sexual kinks and has had unprotected cybersex with godai. (*waves* Hi, Dave!) I do not give a flying fuck at the moon that Dave-the-security-screener at the Ontario, CA airport (I think that was where I was...) knows the majority of the contents of my occult library and my 2003-era sex toys. I don't know Dave-the-security-screener. I don't know the security geeks over at AOL. I don't know the Phoenix Sky Harbor security screeners personally, and as far as they're concerned, they don't know me, though in actuality, they're only two degrees of separation away from me. (Sis was bringing home workplace gossip about my luggage for a few weeks.)
But then, I was raised with little expectation of privacy, in the thick of the information age. Not everyone else was.