Refusing to show up was really his only option if he felt the whole thing was a fraud.
If he doesn’t show up, the President pro tempore of the United States Senate stands up and opens the certificates. Zero net effect.
If he said, "These states had fraudulent votes and I will not accept them as valid", people would have screamed and the entire media hate machine would have been unleashed on him, but what then would have happened?
If they count the votes without his consent, you get a constitutional crises, because that is clearly a violation.
It would have attracted necessary attention to the issue, and it would have put a proper taint on this government if he got overruled somehow by the rest of the Senate.
It would have put an asterisk in the history books about how the election was regarded as fraudulent.
And it might even possibly have attracted enough attention that it gets fixed.