[Brian]

I'd do the following on your work Mac before setting up sync or anything like that.

Quit OmniFocus
Open <your home folder>/Library/Application Support/OmniFocus/
(If you don't see a Library folder in your home folder, open the Finder's Go menu while holding down the Option key on your keyboard.)

Locate the "OmniFocus.ofocus" file in the Application Support/OmniFocus folder.
Select it in the finder, then Option-drag it to your desktop, which makes a new copy of the data. Name it "Work Database.ofocus" or whatever suits you.

You can now set up sync as per normal; tasks stored in the "normal" database will be synced; tasks stored in the renamed one will not.

You'll need to open the work task database via double-click in the Finder or something along those lines, but your work tasks'll stay on the work machine without being synced to your other devices. Should keep the security folks at work happy.