FOP2 is a standalone application, it has its own init scripts and it does not depend on FreePBX or any other external scripts.
The error you see is for FOP(1), not sure what you did to disable (or not) FOP1, the best way is to set FOPRUN=false in /etc/amportal.conf , that should prevent the amportal scripts to try to start/restart/reload FOP(1) and prevent that error from showing. But that is a freepbx issue, not a fop2 issue.
best regards,
