I came up with "something else" as a motivation for ML to meet AA in that park.
He had his house set up with all those cameras, 3 in the bedroom. His roommates say he would get ballistic if people moved a chair the wrong way - he was very particular about his interior design.
I think he was streaming things to the internet and that she needed a place to do her webcam thing. It's hard to do in a room with your sorority sisters (although during the day, when everyone's at school is possible - and it's not just the nature of the video, it's also that background noise, etc., is an issue in these SD/SB encounters).
AA used his cameras to lure her to his home. She didn't want anyone who might know her digital whereabouts to know that she was going to a stranger house in the middle of the night OR he told her that he had to be on the down low, due to the nature of his own online presence). At any rate, they may have agreed that it was best if it not be obvious she was at his house all night.
Perfect situation for him to enact his fantasy crime, which he had been planning for a long time. He couldn't lure those Mormon girls from his stake (he was visiting two, I think) and MK would have found him creepy if he hadn't been offering her this "generous" service and use of his house for this purpose.
Clearly, an invention around the facts on my part. MOO. While she had not allowed her parents access to her phone (which caused a delay in finding her texts), it's possible that her phone was trackable from her computer and she didn't want anyone to know where she was headed - not even a roommate.
At any rate, I think there was a lure that specifically benefitted MK, that she didn't want her whereabouts determined. She may have turned off her own phone (and she may have done that on other occasions, when she was out and about and not wanting to be found by her friends). It would be hard to know whether or not this is true, obviously.