I thought this hack was cool myself i'll probably be installing it on my own forum
Here's a screenshot of the added permission

thanks to The Ghost for confirming that an option like this didn't exist
Though i know you can restrict by forums but thats a much bigger task

Enjoy
One more quick note if you disable administrators from deleting posts then they won't have access either... for security reasons all usergroups were set to no... so you have to activate the users you want to have permission

regular members wont' have access either way
g-force2k2