Pence said (paraphrased quote) "the certification vote was mostly ceremonial."

As it turns out, he is technically correct because the senate rules committee changed senate rules before the certification that basically prevented Pence from contesting the certification- according to the new senate rules.

There are some highly suspicious technical legal maneuverings that happened in the senate surrounding the certification. Whether or not Pence was a willing traitor, or was simply out maneuvered by legal shenanigans, and decided to play along with the BS remains to be seen in my opinion.