The problem with anger is that everyone seems to be down on it. I mean, have you ever heard ANY advice in support of anger? Ever? And yet it is a very common emotion. There is hardly anyone who has not felt it. And, yet, there is nobody who really supports the idea of feeling anger no matter how justified it is.
Given that, it is not surprising that Tiru, too, joins the bandwagon of people who oppose the idea of being angry. Or, more to the point, against the idea of expressing anger.
Sellaa idatthu sinam theedhu sellidatthinum il adhanin theeya pira - Tirukkural
Anger is bad even when directed at those it cannot injure; where it can injure nothing is more evil than that - Loose Translation
Of course, expressing anger to those who you are powerless to injure is bad. I mean, come on, do you really think that yelling at your boss is going to have good consequences? OR screaming at the traffic cop who's pulled you up for speeding when you cannot call on anyone more powerful than him in the time-honored 'Jaantaa nahin main koun hoon'? OR at the professor who is guiding you on your research? I mean, really, does it need a Tiru to tell you that expressing anger in such circumstances is a form of suicide that needs an IQ in the single digits to commit?
But what's the big deal about expressing anger where you have the power to injure? Was Tiru worried about your subordinate taking you to HR for screaming at him? OR you suing the traffic cop for racial discrimination or the Prof for harassment? I daresay not. Not only did Tiru live in simpler times when Authority was always one way and clearly defined but also that, if he had conceived of these things, he would have categorized these relationships also as 'Sellaa idam' meaning places where you are powerless.
So, then, what exactly is the evil he warns you of when you are expressing anger at those who are in your power? THAT, precisely, IS the problem. That expressing anger at them could soon turn into bullying. That you would become the sort of person who misuses his power, who ceases to care for their feelings and use them as whipping boys.
The evil that Tiru warns of is the way that expressing anger like that can warp your character. A far worse evil, in his view, than facing the consequences of showing anger to the more powerful. After all, in the latter case, you'll be taught the lesson that it is a mistake by the immediate consequences!