Sir you completely misunderstood the use and advantage of having long endurance SSBN situated nearer to SCS and Pacific rather than based on Indian coasts.
Offence is the best defense.
The future enemy if comes from EAST through sea lanes, have to tackle A&N first, and if we want to bring war to their coast we need to cut down the distance to send these SSBNs. What would you prefer Indian Coast-SCS or A&N- SCS, which is shorter distance. And in case of war, don't you think we should rather have infrastructure at A&N too.
SSBNs are not useless and they just don't caryy nuclear missiles, SSNs can carry them too, SSBN are those which run on nuclear energy, not those
fire nuclear missiles.