I am not up to date yet, but EP 10
If I were Sorata, I'd tell Rita straight away that she's talking to the wrong person.
Rita should tell Mashiro to quit drawing manga, not to Sorata. Sorata should be someone who support Mashiro's decision, not some who DECIDES it.
While Sorata gives his opinion of what he feels Mashiro should be doing, neither he or Rita has any right to stop Mashiro's decision.
But, without those drama, anime wouldn't be so intriguing.