The exec component is a camel component, so you should look into camel documentation for a solution to your problem. I guess you have added it as a SwitchYard extension, so you can use the component, so you should have some knowledge on how to use camel to do Synchronous Processing.
As of now, the exec component (http://camel.apache.org/exec.html) is synchronous, so yes, it is waiting to finish the execution of the scripts. If you need to do Asynchronous processing, split, fork/join or any other EIP to execute concurrently your scripts, you should look into the appropriate EIPs (http://camel.apache.org/enterprise-integration-patterns.html) provided by camel. (http://camel.apache.org/asynchronous-processing.html)
Thanks, but are you able to give me more specifics on the appropriate EIP?
Literally all I'm doing is taking in files e.g. file1.ext and running script.py file1.ext