I absolutely refuse to get into a relationship or be friends with anyone who has BPD, even if it's controlled.
You have that right, but why?
Because how could someone be so moody?
I'm a little conflicted here.  It is totally your choice who you decide to be friends with.  That being said, don't you think it's a bit hurtful to reject someone for something like a mental illness, which they didn't ask for?
Just because you think it's hurtful or a bad idea doesn't mean I should accept that person or speak to them.
I do agree, and you're entitled to who you want as a partner or friend.