If you take the ridicule and the lack of listening far enough, I like suppressed because it implies that there is something to be feared or avoided by the information the person is bringing forward. If one wants to suppress something, the implication is often that it's true, and one somehow fears or wants to avoid that truth. Therefore, there is both the rejection, denialism and refusal to listen, but at the same time the implication that the person is conveying truth or is "well informed" as you put it in OP.
"This meddlesome man Galileo must be suppressed,” murmured the
University fathers as they left the square. “Does he think that by
showing us that a heavy and a light ball fall to the ground together
he can shake our belief in the philosophy which teaches that a ball
weighing one hundred pounds would fall one hundred times faster than
one weighing a single pound?"
Galileo and the Leaning Tower of Pisa (2011) by Alberto A. Martínez.
Dr. Stockmann attempts to expose a water pollution scandal in his home
town which is about to establish itself as a spa. When his brother,
the mayor, conspires with local politicians and the newspaper to
suppress the story, Stockmann appeals to the public meeting - only to be shouted down and reviled as 'an enemy of the people'. Ibsen's
explosive play reveals his distrust of politicians and the blindly
held prejudices of the 'solid majority'.
Description of An Enemy of the People (1882) by Henrik Ibsen.
Put down by authority or force: subdued.
Kept from public knowledge.
Stopped or prohibited from publication or revelation.
Excluded from consciousness.
Inhibited from growth or development.
Merriam-Webster. Adapted, not verbatim.