This is one of those pieces of statutory law that is there for one purpose - to fool the public.
There are statutes that say Congress must produce certain spending legislation by such-and-so time. They often fail to meet the law, which of course only applies to Congress. There is no penalty, there is no statutory remedy. Just an instruction. A wish.
Now, I am not saying that Congress won't use its instruciton to itelf to claim it is bound, BOUND by the rule of law. I'm just pointing out that this particular rule of law has the same force as a grocery shopping list, no matter what those lying schmucks in Congress have to say about it.
For as little as the courts want to get involved regardless of the facts, Pence as pres of the Senate could probably do whatever he wants no questions asked in the counting.