The part about the screen off is what you think it is.
As for the other thing I am not sure. I am going to a bar this afternoon with a wifi ap and will try it out but I don't remember seeing this. You idea of a timeout somewhere is what I am thinking but I will have to look. Have you noticed either of the other two profiles getting enabled at work?
One thing you can do is to specify the MAC address you want the WIFI Off profile to check. This way it only works when you leave the coverage of that specific AP.
Since my home router is all I connect to that isn't on a specific time basis (like when I am in class) I added a variable state to check %HOME is cleared and I clear it when the WIFI Near profile exits. I do this because I have a large house and my bedroom doesn't get great coverage from my router. (pretty much the farthest point away from the router before you enter the attic). You could set up 2 new profiles to scan for you work router and change your WIFI Off profile to ensure a variable set in either profile is cleared before it turns off WIFI.
That sounds confusing the way I wrote it, if you need clarification I can rewrite it.