I agree this would be nice, but it might not be trivial given how the code is written. Major events, (i.e. ordnance availability, hanger goes down/comes up, etc.) flag a change in availability status, but ENY bounces around constantly. My guess is, the program only checks when you send info to the server (change loadout, try to take off, etc). The alternative would be to poll constantly for changes, and HTC may not want the additional network traffic.
just my $.02 
I think colouring items that are unavailable due to ENY limits is a good idea, and it seems to me to be pretty feasible.
The client (the program running on your PC) already polls to get the current ENY values... the list is updated frequently as it is. The only new thing that might need to be polled would be the current ENY limit, which doesn't change that often, and presumably could be picked up by modifying the existing ENY polling.
Also, something like "Minimum ENY: 12" could be displayed near the list if there is a current ENY limit.