Not everything in India is/have to be about an individual's caste at all.
The most plausible and likely explanation is that it is just shortened initials of surname for convenience.
Typically indian teachers have a habit of turning surname to initials to deal with multiple students having same names. Those names tend to be sticky and students just refer themselves with initials in such contexts.
I'd be very much surprised if his official government IDs have initials and not surname.
Not everything about India has to be about caste but this is definitely about caste even though it probably happens on autopilot now.
A social movement throughout TN, has made people give up their surnames and instead only mention their initial, so that no one can tell your caste easily. And everyone just follows that convention now. A remarkable example of a societal wide movement making real progress on societal issues without requiring the force of government.
The most plausible and likely explanation is that it is just shortened initials of surname for convenience.
Typically indian teachers have a habit of turning surname to initials to deal with multiple students having same names. Those names tend to be sticky and students just refer themselves with initials in such contexts.
I'd be very much surprised if his official government IDs have initials and not surname.