I don't think you've understood the half of it . He clearly said that India can retire the SSK but the neighborhood seas were not conducive for it. Not conducive to what ? Submarines or SSKs or SSNs ? Has India opted for a mixed fleet of submarines because it doesn't have the financial clout of a US otherwise we'd have a fully N based submarine fleet or did we opt for a mix because SSKs fit our littoral defence needs ?
I understood every word of it. He is saying exactly what I would have said. Diesel submarines is much more functionally better than Nuclear submarines for Indian needs of fighting in IOR region.
Financial clout is irrelevant here as nuclear submarines are made indigenously, can carry much more ammunition and can do the work of 2 conventional submarines. It also has no fuel cost and made in India completely at lower cost. The cost of imported Kalvari & its fuel over 20 years will be similar or more than nuclear subs.
The real problem of using all N-fleet is:
1) Even minor repairs take long time as the reactors take long time to shut down, cool off, dismantled safely, reattached safely and long time to restart to criticality. In the middle of a major war with Pakistan, aided by Gulf countries, Indonesia, Malaysia etc, India will not be able to afford such long wait times.
2) In wars, one can expect submarines to be destroyed. Diesel submarines are much cheaper and faster to manufacture. Since fuel cost becomes irrelevant if subs are destroyed, the diesel submarines are much more handy during wars due to this. Only during peacetime, nuclear subs cost less due to low operational costs over long time.
3) K-subs can also be loaned out to allied countries like Myanmar, Singapore, Thailand etc to fight off interference of Bangladesh, Malaysia, Indonesia which can't be done with N-subs due to sensitivity of tech.
4) N-subs produce a noise due to water flow as nuclear reactor needs water for coolant and reactors can't be completely shut down as restarting them is complex. Also, the water pumped out will be very hot which creates thermal signatures. K-subs with AIP work on stored energy in fuel cells and don't produce much heat or noise, making them far stealthier
Nuclear submarines are useful for deterring EU, USA in case they interfere as in 1971. They are also useful in acting as underwater station that lays large number of mines, monitors and attacks critical enemy supply lines over long duration deployment such as deploying near Suez or Southern IOR. N-subs have huge payload capacity due to huge size which means it can carry large amount of mines, missiles, torpedoes for multiple functions. However, in direct combat, it is the diesel submarines which are much better due to its quietness and small size helping it stay and move undetected.
This is why India is focusing on mainly diesel submarines. India will always prefer to have diesel submarines in much larger numbers than N-submarines. Both serve their purpose but the function of K-sub is much more useful than N-sub for Indian context