This is not something I read anywhere, but I feel confident about my guess. Karuna - Compassion and Nidhi - the basis. The 'basis of compassion' is the title used for Lord Rama due to his nature. Now we see why Karunanidhi's parents were probably more honourable than him. That said I dont think BJP deserves to benefit any way, they had a long-standing alliance with his party and Karunanidhi's beliefs have always been known to everybody - who else will name one's son as Stalin - probably the most cruel dictator of the past century.
Also if this is a larger question of principle, I dont know what the fight is about. It should certainly not be about Karunanidhi's belief. His beliefs are his own and he has a right for it (even though he should probably get this right while serving jail-time for other reasons :)). So the valid point to fight would be that Karunanidhi hurt the sentiments of lot of people. Not that he holds a particular personal belief. A pluralistic and secular Indian society shouldnt have a difference of opinion regarding this.
