the command-line is correct (exactly like listed on
http://aluigi.org/adv/swat4x-adv.txt) so from my point of view there are no problems.
for the fake players, if I remember correctly unrealfp wasn't able to fill the server because swat4 required some particular crcs or something similar (I tried also with -f and other options without success) so the only effect was a flood of players that join and exit.
are you sure you have not already applied my fixes and/or you are running other third party code (for example my fake players limiter or similar)?