Jailing him for 12 months, Judge Maria Lamb said his mum should be "commended" for her actions, adding it was something no mother would want to do.
"She acted to safeguard others" added the judge.
Trinder said he was "really angry" with his mother at first, but now he fully understood how she felt.
Prosecutor Merril Hughes said Trinder had gone to stay with his mother during Christmas for six days.
"He used his mother's phone and when he left her address, a message popped up on her phone when she was accessing Facebook."
Hughes added: "His mother found a list of message conversations to females. She realised they were from her son's Facebook account on reading them."
Hughes said Trinder, aged 21 at the time, had asked intimate questions and sent messages of a sexual nature.
"His mother was shocked by what she saw and she contacted the police and handed over her phone them."
Trinder was then arrested and two of his own phones were seized.
He told police he didn't have "anything with underage girls" on his phone and claimed he sent some messages "while stoned".
Alexandra Bull, defending, said there were "elements of immaturity which certainly had an impact on his behaviour".
Although the messages were explicit, there was no physical contact.
The court heard he was diagnosed with Asperger's Syndrome at 14 and suffered from feelings of loneliness and depression.
Bull added: "He has used cannabis at significant levels. He puts a lot of blame on the cannabis.
"He is a young man who is thinking things through and he says he wants to help people."
He pleaded guilty to six counts of attempting to incite a child in sexual activity and will be subject to a Sexual Harm Prevention Order for 10 years.
The judge said "You have got a problem and you need help. This sort of behaviour is very serious."
