No that information is incorrect. You have to take special permission with the Indian Navy to go near the volcanic island and only those with official clearance from the Govt of India are allowed on the active volcanic island eg: scientists etc...
In addition to what Rajesh had said I would like to add that thre are trips arranged to visit Barren Islands, the ship donot land on the shore but keeps a distance away from the shore from where you can see the Volcano. For that you donot require permission.
Barren Island and the volcano are easily visible when you are sailing. You can actually go fairly close to the island but you need prior permission to visit the volcano. The islands in their entirety are beautiful but the majority of them is under the watchful eye of the Indian Navy. This applies for many islands in the Andamans.
