He wasn't truly angry because someone attacked him!
That was quite normal.
The universe is like this, and he could completely understand. Didn't he just launch a few himself?
What angered him the most was that he had no way to take revenge.
By the time he saw the attack, the person who launched it had probably been dead for tens of millions of years. Not to mention their descendants, the civilization was likely extinct as well. Where could he go for vengeance? Such cross-time-dimensional attacks often give one a sense of helplessness in avenging.
He wasn't worried about his own safety.
The nearest attack was still 80,000 light-years away, which would take 80,000 years to reach him. He would either be long dead or have moved somewhere else by then. Humans don't live that long, even with continuous self-repair. This didn't really affect him much.
But—
He was so pissed!
He had to retaliate by doing something.
Otherwise, the frustration would remain unresolved.
