They do go on to quote the dictionary again (both from the 1800s and the current version) to define what an "insurrection" is, then say:

We have little difficulty concluding that substantial evidence in the record supported each of these elements and that, as the district court found, the events of January 6 constituted an insurrection.

Also, love how they basically reference what we all saw live here:

Moreover, contrary to President Trump’s assertion that no evidence in the record showed that the mob was armed with deadly weapons or that it attacked law enforcement officers in a manner consistent with a violent insurrection, the district court found—and millions of people saw on live television, recordings of which were introduced into evidence in this case—that the mob was armed with a wide array of weapons.