George Henderson, the County Attorney, is younger than the other men, but seems to have a good reputation. When the men join together in their general mockery of "women's issues," he make an effort to stand up for them, but his good intentions are quickly undone by his own prejudices.
COUNTY ATTORNEY: [With the gallantry of a young politician.] And yet, for all their worries, what would we do without the ladies? [The women do not unbend.] [...] Dirty towels! [Kicks his foot against the pans under the sink.] Not much of a housekeeper, would you say, ladies?
(Glaspell, Trifles, etext.virginia.edu)
He still has room to learn, but he wants to impress the older men and so he joins in with their mocking. In fact, he is the one to entirely miss the importance of the change in Minnie's sewing; he hears the Sheriff making fun of the quilt and echoes the same joke later. Despite this, he is less mocking than the older men, mostly because he is genuinely trying to investigate; it is more his blindness to women's issues than his own competence that sabotages his efforts to find the truth.