False. Whoever says that anger is a sin, or that love cannot get angry is mistaken. What we do with anger can be either used for good, or for bad. People mistake the emotion, with the actions because the emotion is powerful.
I heard the term "fierce compassion". It is through love governing the expression of anger that we allow the destruction of an injustice in order for good to be served. We can forcefully attack a problem that harms others through becoming upset ourselves at the situation. But the huge difference is that we act upon that upset, upon that anger with control, tempered by compassion towards the perpetrator as opposed to exacting upon them feelings of hatred and vengeance seeking retribution to satisfy some angry desire to destroy another. Love does not seek another's destruction, it seeks to provoke and admonish to do good. Do you see the difference?
The focus should not be on suppressing anger, but rather tempering anger with compassion. Find Peace in yourself, and when anger arises, you see through that center of Peace and act with that anger through that Heart, as opposed to your own sense of truth and justice through the limited eyes of the ego which acts as a child selfishly wishing to hurt those who hurt you.
Making others happy is not the goal. Those that seek to do this are doing so for themselves, to make people happy with them. And subsequently they do not ever actually deal with anger in themselves in productive ways, but rather seek to suppress and deny anger. Which then results in passive-aggressive behaviors towards others which are anything but loving. Pity is the near-enemy of compassion, because it masquerades as love, allowing someone to think that is love when it is rather selfishness hiding itself, masking itself. It is merely the "imitation" of love, and not real love.
I don't see those words in that verse you cite. It simply says, " [love] does not act unbecomingly; it does not seek its own, is not provoked, does not take into account a wrong suffered." By "is not provoked", it simply means to contrast with the self-facing ego which cannot see the other and simply reacts from provocation to defend itself, its pride, by harming another to protect itself. That does not mean someone may not be moved to anger at seeing injustice being inflicted upon another and through "fierce compassion", seek to correct the wrong.
There is such a bad idea of what a "saint" is supposed to look like. It's a myth, and an unhealthy one on top of it.