I think Xano and Xana (unlike Amon, for instance) don't view bending as a divider but as a unifying function and that in the hands of good people, non-benders shouldn't feel isolated or afraid. Which ends up spiraling into who is worthy and who isn't, sort of a mess. It would spark something if Bolin and Korra saw a new face at the arena, someone who just got fire bending (to sort of relate to Asami getting it, when they find out). Or are you thinking of the next skip after this?
And who tries to aim for redemption? Xano and Xana?
If Xano did distribute mixtures that could wear off, that would provide some interesting conflicts later on when things sort of explode in the city. I do assume though, Xana wouldn't tell Asami what the mixture does but that Tenzin and Lin need to drink it, which I figure Asami could do easily if she made them some tea or a cocktail and laced the drink that way. I think by then, she has to trust Xana since she already doesn't feel good about taking on three elements and Xana agrees.