The SSH access is for deploying the rtm binary (setup, config, updates). Only one host is allowed to reach servers through ssh via the ssh key in question.

  # cat .ssh/authorized_keys2
  from="213.186.50.100" ssh-rsa AAAAB3NzaC[...]hBIuk57cDxs= root@cache.ovh.net

For harvesting data, the rtm binary is run by crontab, and does send msg. OVH are not polling the servers.

  # cat /etc/crontab
  */1 * * * * root /usr/local/rtm/bin/rtm 46 > /dev/null 2> /dev/null

If customers are not comfortable with that, they can opt out, according to the documentation (removing the ssh key and/or the rtm binary).