Because it is already installed on rom, embedded in cust.img.
You can't uninstall swype even if you have root privileges.
I removed swype in cust.img using Linux.
This is cust.img without swype. -->> http://www.multiupload.com/544T7IZ0LD
1. Download this rar archive and open it
2. Start your phone in pink screen mode
3. Backup original cust.img to your computer
4. Copy "cleared" cust.img from rar to phone
6. Install your own swype
It is tested on Beta1 v1 and v2.