The judge sentencing Ashley Gill-Webb said although his behaviour was "serious" enough to demand punishment, he thought Gill-Webb was unlikely to offend again.
Gill-Webb was found guilty of intending to cause the men's Olympic 100m finalists harassment, alarm or distress by using threatening, abusive or disorderly behaviour.
Prosecutor Helen Shaw said the high-profile nature of the incident and the fact that the world was watching were aggravating factors.
[It was a] once-in-a-four-year event watched by millions of people around the world.
Some of the people who were in that area missed the event and had paid up to £4,000 a ticket.
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In an email to the actor, Twitter said the tweet “has the potential to be misleading in a way that could impact an election”.
The man was detained by security staff on Sunday evening.
The Duke of Sussex will make a speech at the Loughborough University event.