The issue of their discussion of irrelevant here.
But the specific use of the word 'mami' is decidedly casteist here. But in the skewed politics of TN the one is who is referred to as mami will be branded as casteist.

And also those folks, who wear their wokeness on their sleeves should remember, the Dravidian types will eventually come for you and your caste. No matter what! Exhibit B:

And those self-anointed wokes, whose holier-than-thou act is always grating, are no different. But their cabal will always look the other way. This man, if he were on the other camp, would have been called "vile", "scumbag" by the commissars of woke culture.

It is always topsy-turvy in TN. A Kamal who has openly disowned his caste he was born into is called casteist. But a Sathyaraj, who has never uttered a word against his caste that is alleged to have perpetrated caste violence from time to time, is a Periarist, whatever that is.

Many of Sathyraj's movies actually place his caste in shining light. But he never gets called out.
Well, this is a land where even Bharathiar's clarion call "சாதிகள் இல்லையடி பாப்பா" is drowned by those seeking to see him as a "paapaan".