Two choices IMO, 1) if you can afford it, replace the laptop. 2) If you can't afford it, then take up a collection from the attendees. As for adverse incentives, you should always presume that people are honest and good. However, to cover yourself (and it is a good idea anyways), make them fill out a police report. Keep a copy on file for yourself. This would give any would be profiteer pause, as there are real conse…
Something like a little talk about HDD encryption, kensington locks, hidden softwares calling home, webcam taking pictures every 10 seconds and destroyed after a while unless asked to, etc.