It's not complicated at all. Side chain spotted Bitcoingirl's post, attacked LFC and sent message to bitcoingirl, bitcoingirl got scared/moral/ethics/whatever and finally shared PM conversation with side chain (and some other accounts pretending like it is someone else who sent message

) and changed password to look like account was hacked.
I don't know BitcoinGirl.Club that well but he doesn't seem like someone prone to something like that. Leaking PMs to a shit-stirring noob is near the bottom of the list of things a sane ethically concerned person would do.