It isn't like the Democrats would behave much differently. There is no way Trump would have gotten any Supreme Court appointments with a Democrat Senate had they got a controlling vote in 2018 and a vacancy arisen. Any candidate would have been declared a raping bigot and the investigations would stretch out until around 3 days after a Biden inauguration. Incidentally, that was probably the strategic plan behind the Kavenaugh business; if they'd delayed the process until after the November election there was a real chance he could have been entirely borked.
It is routine politics. Distasteful, naked self interest, low on scruples. But nothing special to the Republican party.