Malagasy,Mascarenes and Kerguelen Islands

The Malagasy were great navigators, able to make the trip from Borneo to Madagascar yet ignored the Mascarenes to the north and Kerguelen Islands to the south. My question is, what would be needed for the Malagasy to colonize the Mascarenes and/or Kerguelen Islands?
Kerguelen yes; the Mascarenes however were close to Madagascar and similar in environment. Why the Malagasy didn't colonize the Mascarenes is more puzzling. But I agree that Kerguelen Islands pre 1800's would only have been used as a place of exile.