That's all correct, I believe.
--LX runs a command or _expression_. To be fair, an _expression_ isn't useful. However, you can write --LX ')copy myws' or --LX ')load myws' to start up APL with a particular workspace. That's useful.
If you load a workspace as above, and that workspace ends contains a call to ⎕ARG to parse out the args after '--' (which are the args reserved to the APL program, rather than to APL itself), then the program can do different things depending upon the command line.
My application is as follows:
$ aplwrap -s 17 -w 1220 -h 710 \
--name "GNU APL `apl --version | awk '/Version/ { print $4 }'`" \
--LX ')COPY pkg' \
-- --pkg-manifest system-1
This copies the pkg workspace (my APL package manager) into APL. The package manager then finds the '--pkg-manifest system-1' option, which causes it to read a file named system-1 from the package manager's directory and load all of the packages listed in the system-1 file.