Onno, I'm not sure what you mean by "serverwide".
All sites, when suspended, will be directed to the index file at </home/<reselleruser>/suspended/index.html> so I believe the only sites that will use the one for admin are admin's own sites.
However what I don't know is if the admin user's suspended directory is copied for each new reseller. If so, then we could call it the "master" suspended page for the server.
Is that what you meant?
Jeff