It is my understanding that Hastert only saw the e-mails, which were a tad too friendly but not explicit. The IM's were not revealed until this week, and those were the things with explicit sexual comments.
Yes, but would he be doing this if Foley had a $100,000 in his freezer?
Hastert acted like the manager who believes that ignorance is bliss. It reminded me of an episode of My Name is Earl when Earl tried to tell the CEO of a company that one of his franchise guys had burned down a competitor, and the CEO basically told Earl that the conversation he just had never happened and walked away, telling Earl that he wasn't better off by knowing all of that because it's a lot of hassle to deal with it and having the responsibility to deal with it.
"Denny, FYI, our closeted colleague Mark Foley has been creeping out pages with emails."
He basically decided when told this that he would not follow up on it-- interviewing the other pages, the page in question, other staffers in Alexander's office, parents of the pages, congressmen, whatever. He could have gotten the info and talked to Foley and threaten him with leaking the info to the press if he didn't play ball.