So I emailed Motorsport (BORA) about the use of Loctite and here is the response I got (for a company that is well known with high-end spacers, I feel their responses are a little less then professional).. The responses haven't been rude, delayed or uninformative but they don't seem as professional and lack proper grammar.
"The hardware is torqued to over 100 lbs. if anything is coming loose do you think a little loctite is going to hold anything together? It will do nothing
The studs in the spacer are pressed in. Sometimes when going to remove lug nuts it can hold it up enough that the stud breaks loose inside the spacer. Then there is real trouble. It’s not often but it does happen. Lots of guys use air tools when we specifically say not to. Air tools plus loctite is a bad combo. "
So they never addressed my question about voiding warranty if you use Loctite, but I do agree with some of the things he did say. But what kind of company says "do you think a little Loctite is going to hold anything together"
Anyhow there you go, that is Motorsports Tech (BORAS) answer to why they don't tell you to use Loctite.... Why it voids warranty, well they didn't say.