Hi @Jens_Noma,
You shouldn't be able to do that becase the adminhtml is protected (ACL rules, authtentication) and cron jobs runs in a different area (frontend, adminthml, cron).
I guess you want to get this part of the controller into your cronjob:
$this->processValidationResult($import->validateSource($source), $resultBlock);
You should check how to be able to execute the validation on your job.
(my 2 cents)