PIO to OCI conversion is entirely voluntary? At most you will get a stupid comment at immigration which you could mitigate by printing out the relevant gazette notification.

The forced sterilisation program was during the 1975-77 emergency when civil rights were suspended. It was as close as India had come to a dictatorship and I'm proud of the fact that democracy finally prevailed.

Till 2002 NRIs who had accepted another citizenship were left in a legal grey zone, the PIO scheme and now the OCI card is slowly fixing that. Its far from perfect, but I would not venture to compare it to the 1975-77 emergency atrocities.