Republicans who refuse to certify the election aren’t dispelling doubts; they’re reinforcing them. They’re telling Republican voters that there is good reason to think Biden stole the election, without offering any such reason. The commission that many of the senators say should look into election irregularities is a dodge. If Republican politicians aren’t willing to call the delusion that Biden stole the election what it is, they won’t be willing to say it after a commission report.
There are three potential harms from refusing to certify a valid election, as Boxer did and many Republicans are now doing. First, the effort might succeed in preventing a legitimately elected president from taking office — a catastrophic possibility, but thankfully one that is remote now, just as it was in 2005. Second, by legitimizing the tactic of not certifying election results that displease senators, the effort might keep a future elected president from taking office or at least cause severe political instability. Boxer was the only senator to object in 2005. For a dozen or more senators to follow her example now (and to cite her approvingly, as Hawley has) would raise this risk considerably.
Third, the effort could spread the poisonous and false idea that votes are not counted fairly in U.S. elections. That danger increases the more officials till the ground for the idea, as Trump and many other Republicans have done. What Boxer did in 2005 was irresponsible, and should have been widely condemned. What Republicans are doing right now is worse.