The mob of people who stormed the Capitol building beat a police officer to death. If the mob had reached the rooms with Nancy Pelosi and Mike Pence, I think they would have been assaulted, too, killing them by accident or deliberately. That would have triggered a Constitutional crisis which could have given Trump grounds to keep power.

Was this a well thought out plan? No. But would it have been enough to derail the process of formally choosing the next President? Quite possibly.