Capturing with Composer is often not appropriate for an agent install, and frankly I wouldn't do it. If the agent contacts a server (like most security agents do), there may be unique identifiers/certs/etc generated for each system, and now you're duplicating that across all your installations.
You want to drop the required installer payload (which it looks like you did?) and run that with a script. Don't use AppleScript, you'll want to learn a little bash instead since it's a shell command. Your Applescript has several issues that I won't go into.
The shell script could basically just be:
#!/bin/sh
/applications/secunia/csia -i