Hey y'all. Fish sent me a PM about your problem. I don't get over to this side of the world very often since I haven't played SH3 for ages.
I'm looking into doing an application to take care of the problem you're having. So far it looks like it will be very similar to RSM's prepare function. You'll have to select a saved game (so the program can find out the actual in-game date and time) and the program will comment out all the radio messages after the saved game date and time.
So far all of the files look very similar, except that the radio messages have a date range instead of just a broadcast date, so I might have to do things a little differently. Shouldn't be any major problem, though.
I'd like to be able to give you a time frame for having it done, but that's going to depend on a lot of things. Hopefully soon (tm).