Most succinct & intelligent explanation possible.
Pence elected to follow rules of precedent fit only for honest actors, a perfect and pristine case, where no slate of electors are contested and no objections to affirmation is argued by a single US senator.
If that which is not enumerated in the US Constitution is deemed to fall to the states, then Pence should have forced the several states to come to agreement on their slate of electors, and to negotiate with Pence for a suitable deadline for an agreement, and/or otherwise lose the right to be counted.