Keep standalone bash script app open after run of script
Gathering what's above in the comments, here's what works: Use Script Editor to write a script containing 

do shell script "complete_path_to_start_script"
on quit
    do shell script "complete_path_to_quit_script"
    continue quit
end quit


Use Script Editor to export the script as a standalone app which remains open after the start script has terminated. This option can be selected in a checkbox.