Suppose, despite the current allegations of sexual assault, Kavanaugh gets confirmed anyway by the current Senate. If the November midterm elections result in a majority in both House and Senate, he could still be theoretially impeached and removed from the Supreme Court, based on that compelling evidence of perjury, couldn't he? In that case, confirmation of someone as potentially impeachable as he, at this point, might actually be more advantageous to the Democrats than the confirmation of another equally or even more conservative, but unimpeachable nominee.
Despite compelling evidence of multiple counts of perjury, the Republicans on the Senator Judiciary Committee have shown no concern thus far over these facts, nor of his advice during the Bush administration that a president should not be subject to any criminal proceedings while in office.
President Donald Trump could have chosen any of a number of staunchly conservative judges who haven’t voiced an opinion that presidents should be beyond the reach of criminal justice while in office, and who haven’t committed perjury multiple times in testimony before the Senate.
In the past, far lesser revelations have resulted in the withdrawal of a nominee, or rejection by the Senate. But the current Senate leadership seems more concerned with pushing forward partisan political views than with assuring that a nominee appointed to a lifetime seat on the Supreme Court has respect for the justice system and has not himself violated federal laws. Nor has the President shown any concerns about his nominee's serious legal and ethical lapses.