The defendant had pleaded guilty to committing public nuisance and using facial covering in an unlawful assembly on October 20, 2019, when protesters tried to block roads near Jordan Road and Ferry Street.
Kowloon City Magistracy said a deterrent sentence was needed as his action had affected other people and society, adding the use of facial covering was an aggravating factor.
But magistrate Cheng Lim-chi accepted his lower-than-usual intelligence as a reason for mitigation.
The man was slapped with an eight-week term for covering his face and a seven-week sentence for causing public nuisance, to be served concurrently.