A man is unable to bring revolution has two interpretations:
It is a real-time "football commentary"-type observation on the activities of an unidentified man.
It is a general statement about any given man, and may imply contrastivity: that other people, like women, can do it.
Crucially it does not mean one man alone. The sentence may be talking about a man trying to start a revolution on his own, or a man who has rallied support. You can express one man alone as a single man as you have done or as one man is unable to bring revolutionby himself/alone.