That is a big no-no!
Only third party software (on top of VIOS code) that is allowed AFAIK are multipath storage drivers like powerpath, SDD, SDDPCM, ... Openssh is provided in the base VIOS code as of 1.3 level I believe.
They *would* find out when you encounter a problem and have to provide a snap file. Their response would then be somethin along the lines of: "Reinstall VIOS without that extra software and see if you encounter the same problem. Then get back to us. Thank you for calling and have a nice day". ;-)
HTH,
p5wizard