CA XCOM for UNIX is designed and implemented to run under effective "root" userid. Any change or reconfiguration of this is not supported.
The xcomtcp process is started as root and verifies the userid and password of incoming transfers. If they are correct, the process is switched to the userid to run the transfer. If the xcomtcp permissions are changed, switching to the incoming userid would fail, so the transfers would fail.
This is the correct definition:
txpi stream tcp nowait root /usr/lib/xcom/xcomtcp xcomtcp REMOTE 0txpis stream tcp nowait root /usr/lib/xcom/xcomtcp xcomtcp REMOTE 0 SSL