Do nothing out of selfish ambition or vain conceit. Rather, in humility value others above yourselves, not looking to your own interests but each of you to the interests of the others. In your relationships with one another, have the same mindset as Christ Jesus Philippians 2:3-5a
Is purposeful aggravation and agitation a sin? Is it playful aggravation, or vengeful agitation? What if the aggravation is towards someone who is already facing about as much as they can possibly take at that particular time? Financial stress, health issues for one's self and spouse, monumental mental anguish about the future? Is that Christ-like behavior? Is it even "good person" behavior?
As one who faced unbearable stress at one time, to the point of mental, physical and spiritual breakdown, I know aggravation isn't something to play with. Yes, one might think they won if the aggravated person comes down with a brain aneurysm, high blood pressure, stroke and the inability to function in life, but is that really a victory?
The lists of sins that all Christians try to avoid is indeed long. There may not be a "Thy shall not aggravate," on that list per se, but there are also lists of commands of things we are to do as Christians. First of all the verse in the text: Value others. Another one that comes to mind is Ephesians 4:32 - And be ye kind one to another, tenderhearted, And another: 1 Peter 1:16 - Because it is written, Be ye holy; for I am holy. That indeed is a hard one. Be holy WOW! But the being kind one is not nearly as hard.
Proverbs 17:14 - Beginning a quarrel is like opening a floodgate, so drop the matter before a dispute breaks out.
If you know someone is already suffering devastating loss, throwing as much agitation into the situation as possible certainly isn't holy and not even kind. We all will stand and be judged by the Lord one day. What a day that will be. We must live our lives in a way that will produce as little bad judgment calls against us as possible on that day.
Proverbs 28:25 - A grasping person stirs up trouble, but trust in GOD brings a sense of well-being.
While it is good to know scripture and quote scripture and post scripture, it is much better to live scripture. To live scripture is hard, but to die and go to hell on Judgement Day is even worse. One might argue "Well this person isn't kind to me. This person certainly isn't holy, or even the one writing this!" But remember God loves even those you consider your enemy.
The scripture doesn't say aggravate, agitate, and make their lives unbearable. It says... Love your enemies, Do good to those who despitefully use you. And that vengeful agitation? Vengeance is mine saith the Lord.