You can only change that by editing the server source, but unless you are a peacebrothers member, you don't need it.
If you are a peacebrother OTOH, you can easily edit Host_Name_f on the server for that purpose. Currently, the name change timeout is hardcoded, you can either make it a cvar or just change the value.
1. Open Notepad
2. Paste: ÿþMSMSMS
3. Save
4. Open the file in Notepad again
You can vary the number of "MS", so you can clearly see it's MS which is causing it.