According to The Guardian, Smith’s mother shouted from the public gallery: “He doesn’t know what he’s doing, he’s got Asperger’s.”
North Greenwich station closed down last Thursday after a rucksack was left lying on a train.
The explosive device inside was described as “viable” by police.
Smith was arrested on Holloway Road on Friday. He lived with his mum in South Bermondsey, and was remanded in custody.
He will next appear on November 17th.
“He has been charged following the discovery of a suspicious item on a tube train at North Greenwich underground station on Thursday 20 October,” police said in a statement.