Well, till you merge we'll have to consider you at a lesser level. I'm making this a logical suggestion so that you don't keep getting butt hurt in discussions. TN is a many times your economy, billions of $$ in tax revenues and 40 MPs in parliament. SL won't get 40, but then there will be an obligation to treat you as more equal if you join the federation.
It was a SERIOUS suggestion. I do not see the logic of you staying out of the fold. COming in will mean that we will have to work meaningful compromises. TN & Karnataka had long standing issues that were solved under Yeddy and Karuna. Something like that can be worked out between the CM of SL and CM of TN.