I think it's great that you have been contacting people sunnynz!
I would draw the same conclusions about a non-reply possibly meaning they know something and don't want to put a denial of knowing her in writing. However, I also want to give them the benefit of the doubt. If a stranger from outside the US messaged me on fb to ask if I knew a woman who committed suicide, I might not reply. I might even go so far as to block that person on fb. Even a seemingly nice person like you. Try not to take it personally. Some people spook easily. The important thing is you tried. Maybe he doesn't know anything but will look into the case and get back to you in a few weeks. Maybe he will become interested in doing a new film that includes Lori's story. Anything that gets more people interested may make the case go viral and help solve this case.
This reminds me of an odd email I received earlier this month. Some woman in Nottinghamshire wanted to book a yurt from me. It was a little spooky because our family had plans to vacation at the beach here in Oregon, & had reserved a yurt for that; & it was also a little spooky because she had the same last name that I have -- which is an uncommon one. Anyway I ignored it, assuming she had simply typed in the wrong email address & the next email she wrote would have the right address. Besides, not answering it was the easiest solution, since it wasn't my problem.
However, she emailed me a second time about it, which prompted me to reply & tell her she had the wrong person. I figured she was going to keep emailing me about renting a yurt (which I couldn't help her with) until I did so.
Maybe in this case, the persons SunnyNZ need a second contact to prompt a response. Maybe they assumed this was just some odd person contacting them about something neither remembers very clearly. Or maybe the relationship one or both had with her was something they find difficult to talk about, & ignoring SunnyNZ was easier than talking about knowing LEK.
Anyway, thanks to SunnyNZ for at least trying.