Just a guess, but I am thinking that the bigger issue here, as stated earlier, is jurisdiction. A ruling that CO has no jurisdiction in Federal elections prevents other challenges later on that might not rely only on the candidate being charged with insurrection.
This would be a broader ruling that states cant deny candidates from ballots.
I always thought that was or should be the central issue.
It also allows SCOTUS to avoid identifying “What is insurrection” and going down that path.