You're a bit too trustful towards the flawless functioning of the scientific community. Scientists are humans and are prone the same group think errors like everyone else. Historical examples are plenty, e.g. Darwin was ridiculed by his peers about his theory of evolution, or the more recent erratic theory that coronary diseases are purely caused by eating too much fat and not by sugar.
In this case, as the article mentions, there was a conflict of interest as well that might well have motivated some leading scientists in the field to campaign against the theory that the Wuhan lab was the source of the outbreak.