If you look, most of the servers on the master list are on 28070. Now, there may have been a particular issue with your setup, but using port 28070 (default) by itself doesn't cause the master list problem. Does the in-game master list include servers that are passworded? I haven't taken the time to look. If that's true, then that could be part of your problem. Did you remove the password prior to changing the port by chance?
Regarding the script, there's no option for a listen server (+set dedicated 0). It doesn't take into account that someone might be running more than one screen window. It also doesn't provide for auto-restart in the event of a crash. I'm sure all those features can be added. I guess I'm just too direct, because using a script of that size to startup my server when I can just use a command line inside an auto-restart script that's 5 lines long (includes logging) seems like a waste. But, it's whatever works for you.