If Moore wins, after all the controversy he's been throught, the Senate cannot afford to vote not to seat him, GOP ssnators coudn't afford to vote him not to seat. The people of Alabama would be furious, they would tell the GOP's establishment is no different from the Democrats.
But if he seats, he would be a national embarassment, the democrats could use him in countless adds, it would bolster their claim that the GOP is waging a war against women.
And if Jones wins, that's one more seat for the Democrats, a thinner majority for the GOP and a defeat for Trump since he endorsed Moore.