The issue is how the constitution lays out the choosing of a president. Pence had to certify the results, if he had refused to do so for long enough, then that session of Congress may have ended without choosing a president.
At that point, the Constitution prescribes there is a contingent election in the House, where every state delegation to Congress gets 1 vote. There are more red states than blue states -> Trump wins.
But if you could see them, they could see you ...