Is it permissible to refrain from denouncing some people with regard to some disliked (makrooh) actions, in order to soften their hearts?.
This does not apply only to makrooh actions but also to some sins. For example, a man may be committing some sins and not others. So he should start with those which are more serious then move on to those that are less serious. For example, if there is a person who does not pray, and he disobeys his parents or there is the suspicion that he drinks alcohol, or some other sin. The one who wants to advise him should start with the issue of prayer, and explain to him how important it is and that not praying is kufr. If he starts to pray, then the one who wants to offer advice should explain about the other wrongful actions, if he thinks that there is some benefit in doing so. If he thinks that denouncing all of them will not affect the goal and he hopes that Allaah will guide him with regard to all of them, then there is nothing wrong with doing that, because Allaah says (interpretation of the meaning):
“So keep your duty to Allaah and fear Him as much as you can”
Hence the Messenger (peace and blessings of Allaah be upon him) called people to Islam and called them to give up shirk before he denounced the evil actions less serious than shirk that they were committing.