This forum is only for reproducible bugs with csf and lfd (i.e. not iptables problems, lack of understanding how to use a feature, etc). Posts must be accompanied with full technical details of the problem and how it can be recreated. Any posts not adhering to this, or not considered bugs, will be moved to the General Discussion (csf) forum.
That option doesn't enable/disable mod_security checking by lfd, that is the option to choose between permanent or temporary blocks. You should set LF_MODSEC to 0 and then restart lfd.