No one knows the reason no one chose to sign him. He may have been fat as f**k and unfit, it may have been the court case, he may just be shite. Who knows.
And as I said, I don't think convictions matter if you're a footballer tbh. Griffiths, Stoke, Jones, Foran, Callum McGregor, Higdon and about a thousand more all have convictions and had no bother getting clubs.