I had a friend who arranged a trip there this past December. He had corresponded with the authorities for a few months and had done the required application for a
permit, which he was told was no problem.
However, after arriving in Mahé and seeing the authorities he was informed that the
permit had been withheld as he had not made provision for armed guards aboard his 53' cat, which he informed the authorities he had no need for. They refused his permit. They claim Aldabra is in a
piracy area and all vessels proceeding there need to hire armed guards - no guards, no permit! This, to me, sounds like a scam for "jobs for friends" as there has been no
piracy in the area for years.
Hope you are successful in your application as it is a fantastic island. The only problem I had around 12 years ago when I stopped there in my way to Dar was being eaten alive by mosquitoes! I had no permit then.