Well, well..
Here we are, at version "10.4.4" and still Plesk cannot play nicely with SELinux. Oh come on Parallels.. Upgrade from 10.3.x to 10.4.4:
type=AVC msg=audit(1327633857.275:37059): avc: denied { append } for pid=28059 comm="httpd" path="/usr/local/psa/tmp/rc_actions.log"...