In some helper applications, they have been denied due to them being staff on another server. Look at the staff now, they are mostly inactive even when they aren't staff on another server. Please be fair with them, they might actually be a great helper, you need to get to know them. Please don't just deny it because they are staff on another server. If they can manage to get on for atleast 5 hours, that's great.
It has been a policy for a while, and if they are an active member of staff, there is more likelihood for something we call "conflict of interest"