What is the ruling on refraining from enjoining what is right and forbidding what is wrong for fear of being scorned or hated by the one being enjoined, or of being exposed to embarrassment and advised not to be overly strict?

What you mentioned is not an excuse for abandoning enjoining good and forbidding evil. The blame, reproach, and accusations of extremism from a transgressor do not negate the obligation to enjoin him. Ibn Rajab said: If one fears abuse or hearing bad words, that does not negate the obligation to enjoin evil, as explicitly stated by Imam Ahmad.